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Bullet Seating Depth
bambambam
Member Posts: 4,818 ✭✭✭
I am starting to load 7mm Rem Mag. I'm new to metalic loading as I've stated in other questions ,so take it easy. I used a spent case(dud primer and no powder for safety) and a bullet seated "losely" and I chambered it in my gun a few times to get an idea of my chamber size.(I pulled it out long each time I chambered so it would compress to chamber size) I got a consistant 3.425". I was on the phone today with tech's from Hornady and Hodgdon(I'm using 162gr Hornady's and H1000) and one told me that the 3.290" COL for 7mm rem mag wasn't always the "rule" for length. He said he seated his 7mm rem mag .020" of the lands in his 1962 Model 700(which he thought was ~3.390"). He also told me he did this because his gun lost a lot of gas between the cartridge and throat because of the gap, which equals less FPS. He said he could load in his specific gun 5grs more in a Win. case because he seated out further and it left a larger cavity in the case for the powder(cheaking for pressure signs.)My COL would be ~3.405" which is well over the standard 3.290" that I think most factory ammo with ~160gr bullets are used. I did notice that the smaller bullet weights had a seating depth of 3.150"- 3.250" because they aren't as long, and I understand I probly won't be able to seat them all the way out to the .020" off the lands. What do you all think about his information on the COL and .020 off the lands?
F.Y.I. Remington Model 770
3.405" leaves me .035" room in magazine.
F.Y.I. Remington Model 770
3.405" leaves me .035" room in magazine.
Comments
The "Constants" are the length of loaded round that will fit the Magazine--Sounds like you are fine there.
The length of your chamber as it relates to the Cartridge Mouth--This dimension is a hard figure and all kinds of bad things happen if you exceed it.
The total length of the chamber with a seated bullet, to the rifling.
Now you have been given advice to back the "Bullet" off by .020. That means you will be skipping the bullet that .020. That just may be the perfect place for your rifle, only testing will tell for sure.
I like to start my load workup by seating the bullet out far enough ---Remember the Mag length--- to Engage the rifling, no skip at all. I do that because I don't own a single rifle that doesn't shoot best this way--Not A One. I always test and test and always let the rifle "TELL ME" what it wants. It is a losing proposition to try and tell the rifle what it is going to get. In doing that you must take published Data with a grain of salt and use it as a starting point, or rule of thumb and work up your loads from there.
Your adivised .020 may be what your rifle says, but until you test the possiblities you will never know for sure. Good Luck !!
RS
Your OAL should allow feeding from the magazine.
You have a hunting rifle and a lot of match rifle reloading techniques won't make a difference and the rest of them probably won't make a serious difference. The main thing is to be sure your ammo feeds reliably, chambers freely, extracts without pulling a bullet when you unload, and shoots with reasonable accuracy.
Your bullets should be seated at least somewhat off the lands to avoid funny pressure effects.
Your OAL should allow feeding from the magazine.
You have a hunting rifle and a lot of match rifle reloading techniques won't make a difference and the rest of them probably won't make a serious difference. The main thing is to be sure your ammo feeds reliably, chambers freely, extracts without pulling a bullet when you unload, and shoots with reasonable accuracy.
quote:Originally posted by Gunny0321
There are a couple of things that need to be considered a "Constant" and after that it is just plan old commomn sense. You also can just go by the published data. I personally like to Tailor my loads to the rifle.
The "Constants" are the length of loaded round that will fit the Magazine--Sounds like you are fine there.
The length of your chamber as it relates to the Cartridge Mouth--This dimension is a hard figure and all kinds of bad things happen if you exceed it.
The total length of the chamber with a seated bullet, to the rifling.
Now you have been given advice to back the "Bullet" off by .020. That means you will be skipping the bullet that .020. That just may be the perfect place for your rifle, only testing will tell for sure.
I like to start my load workup by seating the bullet out far enough ---Remember the Mag length--- to Engage the rifling, no skip at all. I do that because I don't own a single rifle that doesn't shoot best this way--Not A One. I always test and test and always let the rifle "TELL ME" what it wants. It is a losing proposition to try and tell the rifle what it is going to get. In doing that you must take published Data with a grain of salt and use it as a starting point, or rule of thumb and work up your loads from there.
Your adivised .020 may be what your rifle says, but until you test the possiblities you will never know for sure. Good Luck !!
RS
I would start with a 175 gr bullet! ( probably a flat based spitzer type bullet)
H4831 powder as first selection!
Don't worry about bullet jump yet! Go by the OAL recommended in the manual!
Load 3 at minimum powder load, 3 at average middle of average of low and high charges, and 3 at 1 gr below max!
Test 3 shot groups and let barrel cool between groups!
When it starts producing decent groups, then play with OAL bullet jump! But most hunting type guns in the larger calibers are not very selective to reducing a group size very much by trying to find a OAL for achieving a excellent group if it's not shooting a decent group when first testing! (do not expect large changes in group size by changing the jump OAL) Powder selection, bullet selection, proper glass bedding, and the shooter will make more of a difference for good groups than going for jump and OAL at first and you may find that your gun really don't care what the OAL is if it's already producing a good group per the reloading manuals! Some of the larger caliber hunting guns have a long throat and .020 jump cannot be achieved and the case still feed through the magazine box! (and do not be concerned about crimping a bullet if you go by the manual OAL. (If you desire to crimp use a bullet that has a crimping cannulure and then your OAL is automatically selected by where the crimp cannulure is located on the chosen bullet! You don't need to crimp unless you are going to get the bullet close to the lands, which I don't recommend doing for a hunting type rifle, due to possibly leaving a jamed bullet in the throat rifling lands upon extraction, etc, while hunting and you are then SOL![;)]
Curious, why the 175gr choice[?] I was thinking 140-160gr was the ball park for my use. I went to get my compents from local and he was out of H4831, but I payed for a pound and will get it soon...Just playing with what I got for now.
I think you got something there about puting the carrige before the horse. I'll shoot the varying weights first to get a start. But, I had another method in mind. I can't remember the guys name,(think its Audette) he was the guy who invented the ladder method or incrementle load. Another person on GB Forum posted a link on it and I ready liked the idea. I'm going to plink around with 162gr first because I have a new scope to site, but I am going to do the 20 rounds with 3gr increments to find the "sweet spot" for my gun. Then, I think would be time to fool aroung with seating depth.
The POS im shooting could use a bedding ,but i'll sell it before I spend any time doing things like that too it. I floated the barrel just after I bought it. The stock was almost cemented onto the barrel and that was one of the MANYYY problems with it. I'm going to load rounds for the Model 770 to see what groups I get and i'm not counting on it to perform. Probly end up getting a Model 700 and spending some money on a stock with full bed block, but for now i'll have to "dance with who brought me"[;)]
quote:Originally posted by Okie743
For starters when first testing your gun I would consider doing the following!
I would start with a 175 gr bullet! ( probably a flat based spitzer type bullet)
H4831 powder as first selection!
Don't worry about bullet jump yet! Go by the OAL recommended in the manual!
Load 3 at minimum powder load, 3 at average middle of average of low and high charges, and 3 at 1 gr below max!
Test 3 shot groups and let barrel cool between groups!
When it starts producing decent groups, then play with OAL bullet jump! But most hunting type guns in the larger calibers are not very selective to reducing a group size very much by trying to find a OAL for achieving a excellent group if it's not shooting a decent group when first testing! (do not expect large changes in group size by changing the jump OAL) Powder selection, bullet selection, proper glass bedding, and the shooter will make more of a difference for good groups than going for jump and OAL at first and you may find that your gun really don't care what the OAL is if it's already producing a good group per the reloading manuals! Some of the larger caliber hunting guns have a long throat and .020 jump cannot be achieved and the case still feed through the magazine box! (and do not be concerned about crimping a bullet if you go by the manual OAL. (If you desire to crimp use a bullet that has a crimping cannulure and then your OAL is automatically selected by where the crimp cannulure is located on the chosen bullet! You don't need to crimp unless you are going to get the bullet close to the lands, which I don't recommend doing for a hunting type rifle, due to possibly leaving a jamed bullet in the throat rifling lands upon extraction, etc, while hunting and you are then SOL![;)]
BYW... Does anyone think that H1000 smells like starting ether?
I normally would not start with H1000 powder!
Reason I mentioned the 175 bullet is I've seen 7mm wby's that like the max gr 175 gr bullet weights and the groups tended to open up as lighter bullet weights were selected!
When first testing a hunting gun for accuracy (to see if it is capable of any accuracy, I like to use what usually is most desirable for that caliber per the barrel twist rate, what's worked for me in the past, etc! After I find that it's capable of accuracy that I desire, then I test other things later, like lighter bullets, other powders, bullet jump, etc! Glass bedding is not a biggie and you can research such on you tube. Brownells has some real good articles on how to test that the action IS NOT warped after the bedding! (the action is glass bedded dead to the stock with no movement on a dial caliper when tightening and loosening the action stock screws)
Main thing is too have fun playing with reloading and accuracy!
A accurate gun will make a hunter, shooter bring out his best. A non-accurate gun will make a good hunter shooter look and feel bad. A shooter can be no more accurate than his gun set-up is capable! (and more so with target shooting)
I would like to see any "Hard" evidence that seating a bullet out to engage the rifling promtes "Funny Pressure Effects". Seating a bullet out to engage the rifling has been done for hundreds of years. Muzzleloaders by there very nature have to engage the rifling, some of the most accurate rifles in the world are Muzzleloaders. The sport of SCHUETZEN which has been around for at least 140 or so years has almost always seen shooters, using BP as well as Smokelless today, Breach Seat there bullets. In breach seating a bullet it is by the use of a breach seating tool pushed into the rifling sometimes by as much as the bullet length. In this discipline of shooting the ISSA governing body also allows that the bullets can be inserted from the muzzle, so that the projectile has the full length barrel rifling imprinted into the driving bands of the bullet before the cartridge case is inserted into the breach of the rifle. Most SCHUETZEN rifles are Center Fire by the way although there is a huge following of rimfire SCHUETZEN shooters. Pressure is what makes the bullet take that trip downrange, you want as consistant amount of pressure as you can get, that is what makes any rifle accurate. If you have pressure spikes than the velocity will change, velocity change equals an "INaccurate" rifle or different points of impact for different pressure loads. I shot my reloads for my Class F rifle over a Chrony at least once a month in a practice session. I always average a 20 Shot string-Always!! My Extreme Spread is 7 FPS and has been for over a year in this rifle. All of my reloads engage the rifling by .015.
Also tried and true reloading techniques that work well in competiton rifles will work just as well in a "Hunting" rifle. Why would they not? A rifle is a rifle, the same theory and laws of physics able equaly to both. Most competition rifles started life as Hunting Rifle Actions, sure they have been trued up and blueprinted to take advantage of every step that will make them as consistant shot to shot as possible, but in the end they are still just a rifle. Now with that said we as target shooters do have techniques that are simple NOT pratical in the field. As mentioned here you do have to unload a hunting rifle from time to time, so it is nice when the bullet comes out with the cartridge, maybe in your hunting rifle you will need a little more neck Tension than a competiton rifle. You also do need to be aware of your OAL as it applys to the Magazine. But within a little common sense an accurate load and a usuable load don't have to conflict with one another.
RS
You wrote this is a above post and very well said!
I always test and test and always let the rifle "TELL ME" what it wants. It is a losing proposition to try and tell the rifle what it is going to get. In doing that you must take published Data with a grain of salt and use it as a starting point, or rule of thumb and work up your loads from there.
I keep a record of ALL my groups tested, even the very bad groups and especially from a gun that is not grouping to my specs.
The main reason I do this is I have at times went back, several days later reviewing the logged data and read the data and seen a combo of bullet weight, bullet type, name brand of bullet, noted if the group was shot from a cold barrel, warm barrel fouled barrel, powder type, etc, that I had not noticed during the first test and tweaked the combo, letting the gun tell me what it wants instead of me trying to tell the gun what I want it to use!
I sure would have liked to have had internet access to some of the good advice posted in these forums several years ago, stating most of the things that I learned from school of hard knocks during testing and reading books and still having fun testing today learning new things and getting others ideas about achieving accuracy tips!
Just keep in mind that the same recipe that works in others gun don't mean that your gun will like such! (it's just a starting point)
There is one thing you said in one of your earlier post that I see a problem with. That is your three shot group-- I guess we could call this prelimanary testing. In shooting your three shot group as a prelimanary test you are in truth only shooting a two shot group. The first or cold barrel shot is almost always a "Lost" shot in any form of group testing.
Now with that said in a hunting rifle or in a working rifle. You sure better know where that Cold Barrel shot is going. In one if you don't know you can go hungry in the other, well lets just say in the working gun it's real important to know where that cold barrel shot is going, if you want to be around for longer than just that shot.
So while I do see a great value in "Your" prelimanary testing, I feel it should be at least a mininum of (4) shots taking into consideration that the first cold barrel shot may very well have no relationship at all to the other shots that go into the group.
Thus and since it is very important to know were that cold barrel shot is going in a hunting rifle, my suggestion would be to shoot all cold barrel shots into a separate group. This allows you to shoot cold barrel groups and not just toss the first round or the first round after cool down away. This should be a much better way to do prelimanary testing--- In MY Opinion.
In the testing of possible loads, or the working up of loads, we as shooters are trying to determine the "Best" possible accuracy the rifle is capable of. We should never element any loading or shooting technique that may tell us what we need to know. I always start my load testing with the bullet ingaged into the rifling---I mean we have to start somewhere, I just start in the place that seems to work almost all of the time, and as I said works best in every rifle I own. That doesn't mean that if I don't achieve that accuracy goal that I won't start seating my bullets deeper and skip them, I surely would. I start in a place that through "Experiance" I have learned is a real good place to start, never have I been adverse to trying ANYTHING in that goal to find the perfect load. Someday maybe I will find one.
RS
I use the bullets in the lands method and work up for mine. Just because it's a 7mm doesn't mean it needs a 175 gr. bullet. What you need to find out is the twist. That will dictate what bullets/weights you want to use. More weight usually means longer bullet. Length is generally the factor for determining twist. So find the twist and that will give you an idea what weight you want to start with. Just remember the pressure curve goes up slightly when the bullets are started in the lands. There isn't much of a funny curve to it, it's very consistent. But, it does go up. Also, depending on the leade of your rifle you may not be able to seat bullets out to the lands. In which case you will need to make the jump no matter what.
I suggest working up a load with with the bullets at or into the lands say .010". Work that up running a ladder, 2x every .5 gr. or so from start powder weight. Work that up to a grain or so over max. When you see pressure signs back off to where the rifle was shooting most accurately before you saw pressure signs.
Also, in today's world, bullet concentricity and barrel quality have gone up. Shooting light for caliber bullets isn't as much of a problem as it used to be. The problem was generally lighter bullets with a slight imperfection tended to rotate around the center of weight not the shape and exaggerate inaccuracies. And, that could tear the lighter bullets apart if it was bad enough. That would also mean that even heavier bullets would lose accuracy if not made as concentric as they are today.
I suggest H1000 too for the heavier bullets, but H4831 will work for the weight range you mentioned.
Gunny,
That's pretty interesting about running the bullets down the length of the barrel to inscribe the rifling for accuracy. I'd bet that works pretty good. Not many folks seemed to understand how good those old shuetzen rifles were. I had read that book by Ned Roberts on that. 'Course I'm a huge .257 fan too....
A grain or so over maximum and look for "pressure signs?"
If I were getting 7 fps ES in my F-T/R, I would kiss it and put it to bed except for matches and very serious practice, I see no sense in burning barrel life by monthly checking. Sad to say, the only ES as low as 10 fps I have seen was with a load that gave "pressure signs" and I reduced it. My BPCR is a different matter, single digit ES is not uncommon.
quote:Originally posted by sandwarrior
Bambambam,
I use the bullets in the lands method and work up for mine. Just because it's a 7mm doesn't mean it needs a 175 gr. bullet. What you need to find out is the twist. That will dictate what bullets/weights you want to use. More weight usually means longer bullet. Length is generally the factor for determining twist. So find the twist and that will give you an idea what weight you want to start with. Just remember the pressure curve goes up slightly when the bullets are started in the lands. There isn't much of a funny curve to it, it's very consistent. But, it does go up. Also, depending on the leade of your rifle you may not be able to seat bullets out to the lands. In which case you will need to make the jump no matter what.
I suggest working up a load with with the bullets at or into the lands say .010". Work that up running a ladder, 2x every .5 gr. or so from start powder weight. Work that up to a grain or so over max. When you see pressure signs back off to where the rifle was shooting most accurately before you saw pressure signs.
Also, in today's world, bullet concentricity and barrel quality have gone up. Shooting light for caliber bullets isn't as much of a problem as it used to be. The problem was generally lighter bullets with a slight imperfection tended to rotate around the center of weight not the shape and exaggerate inaccuracies. And, that could tear the lighter bullets apart if it was bad enough. That would also mean that even heavier bullets would lose accuracy if not made as concentric as they are today.
I suggest H1000 too for the heavier bullets, but H4831 will work for the weight range you mentioned.
Gunny,
That's pretty interesting about running the bullets down the length of the barrel to inscribe the rifling for accuracy. I'd bet that works pretty good. Not many folks seemed to understand how good those old shuetzen rifles were. I had read that book by Ned Roberts on that. 'Course I'm a huge .257 fan too....
Arkie, Sir I agree with your last post a great deal. You are of course right that works in one rifle may or may "Not" work in another. Testing is all about letting the rifle talk to you. It will tell you what it wants, we just need to learn the language.
There is one thing you said in one of your earlier post that I see a problem with. That is your three shot group-- I guess we could call this prelimanary testing. In shooting your three shot group as a prelimanary test you are in truth only shooting a two shot group. The first or cold barrel shot is almost always a "Lost" shot in any form of group testing.
Now with that said in a hunting rifle or in a working rifle. You sure better know where that Cold Barrel shot is going. In one if you don't know you can go hungry in the other, well lets just say in the working gun it's real important to know where that cold barrel shot is going, if you want to be around for longer than just that shot.
So while I do see a great value in "Your" prelimanary testing, I feel it should be at least a mininum of (4) shots taking into consideration that the first cold barrel shot may very well have no relationship at all to the other shots that go into the group.
Thus and since it is very important to know were that cold barrel shot is going in a hunting rifle, my suggestion would be to shoot all cold barrel shots into a separate group. This allows you to shoot cold barrel groups and not just toss the first round or the first round after cool down away. This should be a much better way to do prelimanary testing--- In MY Opinion.
In the testing of possible loads, or the working up of loads, we as shooters are trying to determine the "Best" possible accuracy the rifle is capable of. We should never element any loading or shooting technique that may tell us what we need to know. I always start my load testing with the bullet ingaged into the rifling---I mean we have to start somewhere, I just start in the place that seems to work almost all of the time, and as I said works best in every rifle I own. That doesn't mean that if I don't achieve that accuracy goal that I won't start seating my bullets deeper and skip them, I surely would. I start in a place that through "Experiance" I have learned is a real good place to start, never have I been adverse to trying ANYTHING in that goal to find the perfect load. Someday maybe I will find one.
RS
Good point about the 3 shot groups only being 2 shot groups! I did not mention that during the preliminary testing of groups I also keep a very good log record of where each shot is on the target. I keep a sheet at the bench and write down the shot string location on the log of the impacted bullet on the target, indicating 1,2,3, and first shot cold barrel, 1st group fired, 2nd group, etc.
After I think I have a working recipe that the gun likes and during final testing I make final proof tests firing cold barrel groups and warm barrel groups. The guns cold barrel group is tested to simulate all types of hunting conditions, first shot during cold temps, hot temps, etc! It does take patience to think I have found a good load and then find that the gun will not produce a good 1st shot cold barrel group! I've seen several guns of several different calibers that would shoot a good group AFTER the first shot. I keep a heads up about where the first cold barrel shot impacts the target, during the preliminaries and when testing other recipes, if the warm bigger group tends to be at the first shot cold barrel shot impact area, this is usually a hint that I'm testing the correct powder, bullet etc, to keep the cold, hot groups in same area for tweaking the barrel vibrations! This is one of the reasons why I indicated to keep a good log record of the group testing, because the gun is talking and hinting, and you need a good log sometimes to sit down review the data, reviewing the cold clean barrel shots, cold fouled barrel shots, warm barrel shots, etc.
I noticed that this guy was just starting and new to testing and metallic reloading and like you said he needs to take most all advice with a grain of salt, keep a open mind and don't get locked into one bullet, one powder, etc, and one jump ALWAYS BEING THE BEST! For hunting rifles I also keep a heads up and make sure that during the prliminaries that I'm NOT TESTING a OAL load that will not feed from the magazine on a hunting rifle so as to try and eliminate go-backs!
And yes to the prev question about H1000 kinda smelling like starting ether. Most fresh powders will have the sweeter type smell and a sour vinegar smell might be a indicator of a powder going bad! This is mentioned in some reloading manuals in the powder section! Can be depressing to find that you've been testing with a old soured powder and then a new batch produces different results!
Recipe's I went off of:
Hornady 162gr H1000=56.8gr(2600fps) start 68.5gr(3000) max
Hodgdon 162gr H1000=67.0gr(2800fps) start 70gr(2905)max
NOW HOW IN THE HECK ARE THESE SO DIFFRENT[?] Hornady's Tech. says to crimp and Hodgdon's Tech said no crimp. One reason for the diffrence in #'s. OK. So I chose 63gr(H1000) as start and 65gr(not close to max) as a little "test the deep end before I jump in"...
Ok.. Let me get some info out for you to chew on. Used my Rem. 770 7mm Rem Mag 1:9.25" twist. FED 215, I loaded(10)63gr(rem case) &(10)65gr(fed case) both H1000 , with a Hornady 162gr A-Max. I went ahead and seated them .010 (+/-.005) off the rifling. I have a Lee DELUXE die set with "Dead Length Bullet Seating Die". I'm not inpressed as i'm getting .015 varience in depth.[:(]
As I said earlier,I was sighting in new scope (Simmons Whitetail Classic 6.5-20X50mm). I used the (10) 63gr loads to get my scope where I wanted it at 50yrd & 100yrd. I shot these loads with ease and didn't have any pressure signs and for the 7mm rem mag were moderatly pleasant to shoot. No case or primer indications of caution.
I finished my paperwork on the 10th load of the 63gr batch. My first 65gr load was also on the same paper as the 63gr holes to check point of impact with the 2gr extra.
My first 65gr shot was somewhat louder(moderate) and a little more kick. I instantly picked up the primer deformation though. The primer still had a radius on edge ,but flatter than a new one. I was for the first time seeing what you guys all talk about with the primer starting to flatten out. I used my caliper on the case and didn't have any swelling. I finished all of the 10 65gr loads all ever so slightly flattened primers.
NOW.....How is it(mind you I seated them almost to the rifling) that at 5grs under max load on one, and 3.5gr under max load on the other i'm seeing pressure signs.....boggles me?
Best part was that in my haste to go try these out I left my chrony at home[:(!] I sure have figured out that the published data isn't the gospel, and that you just need to be carefull and pay attention to you gun and cartrige.
You all have really helped me out in the knowledge and experience that you share on here. I really didn't have a clue what I was doing(still don't clam to know near enough) and have learned alot from the advise you share. Thanks..
Also the gun was shooting half gallon milk jugs a 250yrd better than I shoot clay targets at 15yd with a shotgun![:D]
I still haven't done my incrementle load test to get a good group on paper, but I know that I won't have as big a deviation to test as planned with 20(.3gr) increments. I'm guessing 60gr-64gr may be my test range. After all I still have H4831 SC to test and probly Win. LR unstead of the Fed 215.
I can see how fun and addicting this has become[:p]
search "sinclair bullet seating depth tool"[;)]
I think I'm going to call LEE and ask what there tolernce is for there seating die. I was reading there discription of how it's guarantee'd that the die is most accruact seating die made. I don't think the .015 fluctuation i'm getting is right. I may have to send it in for replacement/adjustment.
http://www.sinclairintl.com/.aspx/pid=34262/Product/Sinclair_Hex_Style_Bullet_Comparators
You can research or call sinclair and they can explain it's intended purpose! A hint! Once you find your desired jump for a particular bullet, when you change to a different style or type of bullet you can use the bullet ogive comparator to keep the jump the same by reading off of the bullet's ogive!
Second, seating a bullet at or into the lands increases pressure, sometimes a lot. Whether you call that "funny" or not, it is true, and has been documented by every ballistic lab extant. A short amount of "running room" eases the initial engraving of the bullet and lowers pressure. The real world analogy here is trying to push an axe into a log versus swinging it.
Third, you don't need to know where the lands are; you only need to learn that rifle's most accurate seating depth. Seat all bullet to that same depth and you will be accurate, no matter what bullet shape you use. I am NOT talking about overall length, however, but the distance from the cartridge base to a datum line on the bullet. You only have to keep that distance consistent to maintain best accuracy. And you can do it with a caliper; no fancy land-finding tools needed. Details http://www.reloadingroom.com/index_files/Off%20Lands.htm
What kind of groups are you getting from the gun now with factory ammo or your reloads at say 100 yards?
And what kind of accuracy do you expect to get a the maximum groups size at 100 yards that you can live with!
Reason I'm asking this question is kinda normally for a factory hunting rifle that has not been glass bedded, some guns will shoot a 1 1/2 inch or less AVERAGE group and some will shoot a 4 inch or larger group! If your gun is producing big depressing type groups at the preliminary, moving the bullet back and forth by few thousandths is not the answer! We are not tuning a match grade target rifle for 1000 yard accuracy yet!
Normally moving the bullet back and forth for jump IS NOT a preliminary thing when first testing! (it normally will only average reducing a group on a non-glass bedded hunting rifle by maybe a 1/4 to 1/2 inch. Load up some of your bullet going by the reloading manuals OAL shoot about 5 three shot groups and let us know what you are seeing group size wise!
I've got the truck packed up and ready to go shoot tomorrow, let you know what I find out. This time I packed my chrony.
Keep a heads up about keeping the bullets BETWEEN (inside) the guides, especially not too low![;)]
Might want to check a group first without the chrony too see if it will keep a group between the rods at 10 feet![;)]
Just kidding! Have a good time and good luck to ya!
As I stated in my earlier post I load my bullets ""Into"" the lands because it shoots best for me, that I learned from many years of experiance, and I have seen this not only in my own rifles but in several rifles. I also didn't coin the word "Funny" when it came to pressure I was making a reference to another post.
I also don't have a problem what so ever with your "extant fact"that pressure increases if the bullets are in fact loaded into the lands. I have no problem what so ever with that being the case. That is as long as "I" see no pressure problems or signs of excessive pressure in my rifles and the load is accurate.
I after reading your post today I decided to do a little research on my own. It was range day anyway and I was just sick to death with the building of my new reloading room, so I loaded up and drove the 4 miles to the range and did a little shooting.
I took my Class F rifle in 6mm NormaBR and settled down in front of the 600 yard berm. I had with me my standered match load, and 10 rounds of that same exact load but with the bullets seated "OFF" the lands by .015. My match load the bullets are seated to engage the rifling by .015
This load is
Varget--- 30.3 Grains
Lapua---- 105 grn Scenar
CCI
450 Primer
Brass---- all once fired Lapua
I had the kid who works for me in the shop separate the 20 rounds I was to fire over the Chrony into separate groups and not tell me which was which until after I had finshed shooting and recording the information into my log book, just so that any prejudice I might have would not interfer with the data. I then fired 4 sighter shots to foul and heat the barrel, from a clean bore. I followed this same procedure for both 10 shot chrony runs. The results were:
Ist Run
SHOT
(1) 2928 FPS These 10 rounds shot into
(2) 2950 " group that was 9_ Horz by
(3) 2931 " 8_ Vert for 7 shots one
(4) 2941 " shot was a called
(5) 2947 " shot low right and two
(6) 2929 " unexplaned flyers that opened
(7) 2931 " group up to 12 7/8ths on the vert.
(8) 2948 "
(9) 2937 "
(10)2929 "
Extreme Spread
22 FPS
2nd Run
(1) 2932 FPS This group shot into a group
(2) 2932 " 6 1/8th Vert by 6_ Horz for
(3) 2931 " all 10 Shots.
(4) 2936 "
(5) 2930 "
(6) 2932 "
(7) 2931 "
(8) 2936 "
(9) 2932 "
(10)2932 "
Extreme Spread
6 FPS
Run # 1 was the load with the bullets seated .015 OFF OF THE RIFLING.
Run #2 Was my match load with the bullets seated into the rifling by .015.
With the results from these two chrony runs I see this: Run #1 had an ES of 22 which was 16 fps more than run #2. Run # 2 was an average run for this rifle and this load, it routinely shoots this well and has shot many groups of ? MOA at 600 yards when I do my part and have my head into the game. Run # 1 which was the load with the bullets seated "OFF" of the rifling shot one of the worst groups this rifle has ever shot.
None of these cases showed --nor have the ever shown-- any signs of excess or abnormal pressure. As I matter of fact after shooting these 20 loads over the chrony I mixed the brass together and tried my best to see if there was any differnce at all in the fired cases. There was none that I could see, not in the cases thereself nor in the primers, I then decapped those 20 cases and inspected the 20 primers once again "I" could not see nor tell any differnce what so ever between any of those primers.
Does this very cursory test by a shooter and certainly not a Ballistician prove there is not a pressure differnce---certainly not!! I am not trying to say it does, what I am saying is that over my shooting career that spands many, many years, I have never seen or had a problem with pressure by seating the bullets to engage the rifling---NEVER. I also believe that the History of shooting says that this practice has a very sound basis for those that strive for an accurate load. It has been done by shooters who sought out the most accurate load possible for a least 200 years. That and the results I see for myself on target is good enough for me......
Roland
Having the bullet into the lands at ignition does raise pressures. That doesn't mean that it always and automatically creates excessive pressures, just higher ones. If the load is moderate - as yours apparently is - then the higher pressure isn't necessarily bad. It can even be beneficial if it brings the powder closer to its ideal working pressure - again, as yours apparently does.
The difficulty comes when people work up a load to a high but safe level and THEN start to experiment with seating depth by seating out into the lands. That can be dangerous or disastrous.
The "funny" results (referencing the first use of that term in this thread) are that pressure and velocity drop a bit as you seat the bullet farther and farther out. UNTIL you hit the lands, and then pressure can spike a lot, even if velocity does NOT increase. That truly is "funny" compared to our normal expectations of pressure versus velocity, which normally rise or fall together.
Two things cause this funny business; one of them is proven and the other is my own theory. The proven one is that it takes a lot more force to engrave rifling into the bullet if doesn't get a running start (that wood-splitting analogy I used earlier). The slight delay in bullet movement and the extra force needed naturally cause pressures to rise a lot.
The second - my own theory - is that as the bullet sits there jammed in the lands and partly unsupported, with pressure rising behind it, the bullet obturates a bit. Now it is larger, and a much tighter fit in the bore. This requires even more added effort to get and keep it moving. Result: lower velocity despite much higher pressure.
Just right off i'm going to say that either this gun shoots like sh**, or i'm rusty. It's shooting 1.25-1.375"@50yrd, & 3"@100yrds. I sand bagged the gun and shot good steady shots,mind you the wind I had today and shouldn't even been shooting in it.
I made some loads at loadbook spec.'s on the seating depth(3.300) w/63gr of H1000(H4831SC here today). 6 shot string made 2" @100yrd. Velocity 2630-2663fps. ALL loads today with 162gr Hornady A-Max Moly and Fed215.
Next string 10 rounds w/64gr same powder but 3.410 +-.005. This gets me about .020 off lands/groves. BIG diffence here in velocity. Closer to the rifling the slower I got. 1St shot was the smallest length at 3.405"@2713 fps. Last shot was longest 3.418"@2553 fps.
Went and fired my ladder test today because I really didn't expect anything conclusive to happen after seeing string 1&2 on paper.I fired a total of 20 rounds for ladder test at .3gr intervals(62gr-67.7gr). My target looked like a shotgun blast not a ladder[V]
My velocity ranged from 2602(62gr)-2865(67.7gr). I also noticed some of my larger powder loads where hitting lower not higher???
I guess in conclusion I was disappointed today with my guns accuracy and my peformance behind it. I really didn't get the results I wanted on paper ,but I learned how not to repeat some of them.
I think the Fed215's may need substituted for Win LR and also H-1000 for some H4831SC. I think given a day with nicer weather could result in a better outcome.[V] Also one problem I may have is the box of Hornady 162gr A-Max Moly coated bullets says 1-8" and my gun is 1-9.25".
It's a Remington Model 770.Expecting it to shoot is like sitting on an egg hoping for a gold nuget. BUT, stranger things have happened[:p]
These are what I use for everything from factory rifles, up to my Benchrest and longrange rifles. You can run the test the same way, a hundred times over, and still get the same measurements, right down to the .001"
The best part about the sinclair tool, is that it specifies the use of a FIRED CASE FROM YOUR CHAMBER. That is the key to getting it right. The LEE tool won't be on par with anything made by Sinclair. Their staff is made up of longrange and benchrest shooters. I have had many long conversations with their employees before buying a tool and I can say, those boys know their business.
Buy the sinclair seating depth tool, and the sinclair comparator. THAT will give you all the info you need, clean up to benchrest competion. read the directions and you will understand how the pair of these tools will give you all the info you need as far as seating depth is concerned.
These are what I use for everything from factory rifles, up to my Benchrest and longrange rifles. You can run the test the same way, a hundred times over, and still get the same measurements, right down to the .001"
The best part about the sinclair tool, is that it specifies the use of a FIRED CASE FROM YOUR CHAMBER. That is the key to getting it right. The LEE tool won't be on par with anything made by Sinclair. Their staff is made up of longrange and benchrest shooters. I have had many long conversations with their employees before buying a tool and I can say, those boys know their business.
AMEN[;)]
Thanks, but I still have one thing in mind.
It's a Remington Model 770.Expecting it to shoot is like sitting on an egg hoping for a gold nuget. BUT, stranger things have happened[:p]
It will be ok, just have faith, Remington rifles have good barrels, just don't get it red hot when testing!
I've seen several Remington rifles that would group better than the guy behind the trigger, especially the Magnums! Wear ear muffs and a sissy bag and quit shooting if you get flinchy!
You can place the sissy bag under your shirt bdfore leaving the house and no one will know you have it on![;)]
quote:Originally posted by bambambam
Thanks, but I still have one thing in mind.
It's a Remington Model 770.Expecting it to shoot is like sitting on an egg hoping for a gold nuget. BUT, stranger things have happened[:p]
It will be ok, just have faith, Remington rifles have good barrels, just don't get it red hot when testing!
I've seen several Remington rifles that would group better than the guy behind the trigger, especially the Magnums! Wear ear muffs and a sissy bag and quit shooting if you get flinchy!
You can place the sissy bag under your shirt before leaving the house and no one will know you have it on![;)]
What's a sissy bag?
quote:Originally posted by Okie743
quote:Originally posted by Okie743
quote:Originally posted by bambambam
Thanks, but I still have one thing in mind.
It's a Remington Model 770.Expecting it to shoot is like sitting on an egg hoping for a gold nuget. BUT, stranger things have happened[:p]
It will be ok, just have faith, Remington rifles have good barrels, just don't get it red hot when testing!
I've seen several Remington rifles that would group better than the guy behind the trigger, especially the Magnums! Wear ear muffs and a sissy bag and quit shooting if you get flinchy!
You can place the sissy bag under your shirt before leaving the house and no one will know you have it on![;)]