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Shot out Pro Hunter 7mm Mag barrel?
yukon100jack
Member Posts: 51 ✭✭
I just noticed something strange. I bought a 28" 7mm Rem Mag Pro Hunter barrel for my encore a few months ago off GB. It was used but in good condition. The bore looked fine at the time of purchase. Since then I have been reloading and searching for a "pet load" with 160 grain Accubonds and IMR 4350. In all I have fired less than 300 rounds. Some were 120 and 140 grain Sierra Pro Hunters as well. Accuracy was decreasing over time and by best load with Accubonds has increased from 1" to about 3.5" I went to clean the barrel tonight and noticed what looked like the first inch or two of rifling was disappearing. There are no clear edges to it and the lands look weak in that portion. The rest of the rifling looks fine. All my loads have been below max and I haven't seen any signs of excesive pressure. What could be causing this? What can I do with the barrel now? Help!
Comments
"If slight throat erosion causes poor accuracy, a good gunsmith can " set back " the barrel by cutting off a 1/4 to 1/2 inch and rechambering."
This is a T/C Encore barrel which cannot be set back do to the lug.
Best.
Are you sure that your not looking at the leede angle? This is the transition between the bullet diameter area and the full rifling area and IIRC runs in the 2 1/2^/side (5^ included angle) range
A "roasted" throat looks more like a dried mud flat IE a cracked / crazed surface
When you think it might be clean, run a wet patch of Hoppes Benchrest #9 thru the bore, leave it wet for 24 hrs, then run a clean white snug fitting patch thru the bore! If it comes out green or blue, it's still got copper fouling! Keep cleaning until a clean white patch comes out with no or minimum color!
Then, try H4831 or H4831SC powder and 175 gr sierra spitzer or a Hornady 175 gr bullet! Try to stay with a flat base bullet, solid nose bullet for now! Stay away from boat-tail and hollow points for now! Start at minimum load and shoot 3 shot groups with a NON-HOT barrel! Keep a record of your groups, etc, and sometimes you will see a pattern or things so as you can tune er in!
Also make sure your scope and mount is ok!
Some 7 mags just don't like anything less than 175 gr bullet!
Good luck to Ya!
Note that the 'leade' is a cylindrical section only 0.0002" to 0.0005" larger than the bullet diameter.
The tapered or funnel section is referred to as the throat.
Modern cartridge chambers usually are cut with a reamer utilizing a 1 degree-30 second throat angle.
Best.
I've seen some that were copper fouled and groups were terrible, even losing bullet hole on a inch square paper!
MOST LIKELY YOUR BARREL IS NOT SHOT OUT, JUST ONE THAT NEEDS A good copper CLEANING AND CAREFUL reload TUNING! (the longer barrels like yours in the 7 mags seem to be not as forgiving for easy tuning also!
I've seen some of the 26-28 inch long barrel 7 mags shoot 8 inch groups at 80 yards with $50 a box factory ammo and reloading bring them to consistent 1 1/2 inch and better triangle groups at 100 yards!
Good Luck to Ya
and don't be bashful about using a SISSY bag between the stock and your shoulder and good set of ear protectors!
Too save some $$'s I TEST with a lesser priced bullet at first, such as a Hornady #2830 (154 gr) or #2850 (175 gr) and both are good hunting bullets also, then switch too your accubond and sometimes you do not have to any changes, unless maybe just a slight powder charge adjustment! You will also usually find that the GOOD NOSLER Hunting bullets, Partition, accubond, etc, usually will produce a slightly larger average consistent GROUPING, DUE TO THEM BEING hunting BULLET, NOT match, OR TARGET BULLETS. (for example I've used match bullets and be getting consistent 1/2 to 1 inch groups from HUNTING rifles and then switch to the Nosler Partitions, Accubonds and groups open to average of 1 1/2 inch average! These bullets are made for hunting, not punching paper, so I live with it and use them on large game!
Also be sure the powder for the heavier bullet is H4831 not IMR4831. The IMR4350 that you are testing and H4350 (I use both also and usually favor H4350 over the IMR) is somtimes good also for good groups, but the grain weight can be very critical sometimes, like 1 gr being difference in a 1 inch group vs a 2 inch group, etc whereas the H4831 MAY NOT be as critical to the grain reload weight using the heavy bullets, 175 gr area! Just part of testing, so be-aware of such! You never really know until you TEST! Chalk it up as part of the FUN process!
When you think you have it clean, give it couple strokes with the bore brush loaded with Hoppes and then let it soak for 24 hrs, and then run a clean patch for test! Bore brushing will speed the process but don't over do such! I don't use bore brush any more than necessary!
You can tape a plastic bottle over the muzzle end of the barrel to catch the bore brush exit splatter, etc!
You mentioned eye balling the barrel lands for crud, the blue/green patch will tell you more than the eyeballing about copper fouling and when it's ready for re-testing! Usually once its clean the cleaning process is not as extensive the next time if you will check copper about every 30 shots or so! I've seen some barrels that would take a week to start brings them around with the Hoppe's patch cleaning process! (When you have and appreciate a good barrel/gun, also always run a clean dry patch thru the barrel to remove oil, etc, before going hunting, etc. Do not fire the first shot thru a oily or soaked barrel/chamber!
Good luck to Ya!
A real good way to copper foul a barrel is to shoot it dry as a bone, you really need a bit of lube on that first shot out of a clean barrel.........
Can you refer me too where this is down is writing by someone who knows what they are talking about! (I've never heard of such???
Not in this neck of the woods!
Several reason's to have a dry bore! Read the manuals!
1st is a non oily chamber to reduce bolt back pressure!
2nd is No hydralic pressure from the bullet going down a oily bore!
3rd With a oily bore the first shot may be a flyer, due to non-consistency shot to shot! (and most animals in my neck of the woods don't wait around for practice shots)
4th Fill one up with oil, water, snow, etc and give er a shot and see what you get!
many BR guys leave a light lube in the barrel for the first shot. Not a lot, just a fine coating.
there is not enough oil when applied by a patch, to blow-up a barrel as it would when packed with mud, etc.
There is a product used by BR guys that is patched into the bore before each shot during break-in,...it is called gun juice. It actually forms a microscopic chemical coating on the metal surface that decreases fouling.
clean bore shots on game is not smart, anyone who knows much about rifle accuracy, fouls in their barrel prior to hunting season.
many BR guys leave a light lube in the barrel for the first shot. Not a lot, just a fine coating.
there is not enough oil when applied by a patch, to blow-up a barrel as it would when packed with mud, etc.
There is a product used by BR guys that is patched into the bore before each shot during break-in,...it is called gun juice. It actually forms a microscopic chemical coating on the metal surface that decreases fouling.
clean bore shots on game is not smart, anyone who knows much about rifle accuracy, fouls in their barrel prior to hunting season. What you say here is what I'm referring too for hunting rifles! I suspect the guy with the 7mag encore was going to use it for HUNTING, instead of BR tournments, since he said he is testing Nosler accubond bullets, maybe!
A real world test of a hunting rifle is a first CONSISTENT ONE shot on target from one day to the next in both cold and warm temps.
I've seen several hunting and BR rifles that would shoot a excellent group, AFTER THE FIRST SHOT, but the first shot would be a flyer, most generally due to the wrong powder and or bullet! In my opinion, Real world proof testing is first shot on target consistency for hunting rifles, with 2nd and 3rd shots to same Point of Impact in all kinds of temps,s and weather conditions! (the largest variable being the shooter)
They are not cleaned again until hunting season is over.....
I never said a word about oil in a chamber, that should be dry....
No one in there right mind would intentionally leave anything in a bore but a very light coat of oil before they shot it...
Why even test a bullet that you don't intend to use ??????????????
clean bore shots on game is not smart, anyone who knows much about rifle accuracy, fouls in their barrel prior to hunting season.
many BR guys leave a light lube in the barrel for the first shot. Not a lot, just a fine coating.
there is not enough oil when applied by a patch, to blow-up a barrel as it would when packed with mud, etc.
There is a product used by BR guys that is patched into the bore before each shot during break-in,...it is called gun juice. It actually forms a microscopic chemical coating on the metal surface that decreases fouling.
I call that seasoning, if you were to say that over in the BP forum someone would ask you if you planned to cook a pizza in the barrel becuase that is an old wives tail and does not work [;)][:D]
I practice this technique none the less
Let us know how the barrel is acting when you start punching paper again?
Any of you guys have any experience with using a product called Kroil? (in rifle barrels)
Best stuff ever for lots of things...
Kroil is exactly what I use in my barrels after they have been cleaned, and then a single patch is run into the bore just before they go to shooting again..
Best stuff ever for lots of things...
is the single patch you use just before shooting a kroil patch or ???
I bought a can of it from midway sometime back and been reading about it on the computer links and noticed that it's not recommended as a long term bore lube (like maybe it won't prevent rusting) It appears that maybe it's main purpose is like you stated, bore seasoning,
to help reduce Cu fouling, but I'm not sure if it's a bore cleaner,
Did not want to experiment with it on any of my barrels! I've been waiting to TEST it on someone else's gun besides mine, like maybe Bro in Laws!
You could leave Kroil in a bore for a long time and it will not cause a problem..
I've never had anything rust that had a very light coat of Kroil on it....