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Headspace question
joken
Member Posts: 201 ✭✭✭
This is my first post on this forum. I am just starting to reload. I am using the Nosler manual and have a question(s) about headspace and bullet seating depth. On this rifle Rem 721 30-06, I marked a bullet and inserted it in a case and chambered it as described in the manual. The bullet apparently did not go in far enough to be pushed into the brass even though it was seated only about 1/4" or less. The question then is do I just load to the maximum dimensions in the manual? The brass was sized to meet the specs in the manual. Am I wrong in assuming that this rifle is built to very generous specs so that it will shoot about anything? I've had it for years and it shoots core-loc's quite well. Hope this makes sense. Thanks, Ken
Comments
Maximum accuracy is generally attained by seating a bullet so it is roughly 1/1000 an inch off the lands. From what it sounds like, you were trying to do this. I.e. just start a bullet into a case, ram into the chamber, and measure OAL.
Since your bullet didn't seat, the throat of this gun is such that it isn't going to be possible to seat 1/1000 off the lands. This could be due to the bullet profile, the taper of the throat, or a worn throat. In this case, your only concerns are going to be seating the bullet deeply enough to get proper neck tension and alignment and possibly magazine feeding. If the round will feed through the mag and is seated deeply enough that it takes up at least 1/3 of the neck then I'd say you are good to go.
Headspace is the distance from the bolt face to the chamber shoulder, and the consideration if there is any play between your resized brass and the shoulder when chambered. It has nothing to do with bullet seat depth. If you sized your brass as per instructions and using proper dies, it won't be an issue.
Once you have a good, safe, accurate load worked out, than tweak the OAL slightly to see if you can improve on the grouping.
Stick with either the "tested At" length or the "Max OAL" (off the top of my head, I can't remember if Nosler gives you both), start at the minimum powder charge they give you, load 3 rounds at each 1/2gr interval to the Max powder charge, and go shoot some groups.
Using the powder charg(s) that show the most promise (small groups) reload 5 rounds at those charges and re-shoot. The powder charge that consistantly gives you the smallest groups is the one you want for that powder/bullet/primer/OAL combo (only change one thing at a time).
Is this your rifle that you bought new???
How many rounds down the bore??
Did you mean you loaded to book specs and it didn't hit the lands??
OAL given in the loadbooks is determined by magazine length.
Throat length can and WILL be up to .150 tho. over that..as a Varmint Special Remington that I took out of the box brand new was.
The OAL is never long enough to touch the rifling...without proper tecnique, pressure spikes can occur.
I also find book OAL (as well as being a joke IMHO) is wayyyy short of magazine length. Too many lawyers,...not enough shooters[V]
The hot-rodders are the people that will get into trouble without bullet jump, as you well know..and I frankly don't know what keeps some folks alive, the way they load.
I have listened to tales of handloads crammed full of powder that makes me shudder...and because the rifle doesn;'t come apart immediately that is classified as a 'good load'...
I remember one fellow that had a rifle built by a certain machinist..(not a gunsmith, and he got all his information on how to chamber from a certain "HotRodder")...the machinist said he built the rifle 'just like the one he built for the hotrodder'...
"Bob" borrowed some ammunition from 'HR', was telling me about it. I STRONGLY urged him not to shoot it.
He did so...and welded the bolt closed...on the THIRD shot...AFTER blowing the first two cases out the side of the neck....
The Lord does indeeed look after fools.
Okay...I will accept that. Obviously, the rifle companies determine the OAL from Saami...then build their rifles to accept that magazine..then make damn sure the throat is up to .150 thousands longer then...
Perhaps you will not be so upset if I invert my statement ?
The magazine length is determined by OAL ?
The end result is the same. Quite often, you cannot get anywhere near the rifling with the bullet..and still feed thru the magazine.
quote:OAL IS NOT DETERMINED BY MAGAZINE LENGTH!!!!
Okay...I will accept that. Obviously, the rifle companies determine the OAL from Saami...then build their rifles to accept that magazine..then make damn sure the throat is up to .150 thousands longer then...
Perhaps you will not be so upset if I invert my statement ?
The magazine length is determined by OAL ?
The end result is the same. Quite often, you cannot get anywhere near the rifling with the bullet..and still feed thru the magazine.
No, I will not accept that. If we look at "families" of weapons they generally come in two or three lengths, ie.:short,medium,long. Actions are seldom designed around one, and one length only cartridge. The exception of course are military actions. When discussing the 721 Rem (here), Remington came out with a shorter action-the 722, for shorter length rounds. Bullet companies seldom manufacture bullets with just one cartridge in mind, and when they do, they almost always state this, example 9mm for 357 Sig (this is do to the oal, and the ogive of the bullet). In a rifle such as a 30-06 where load data ranges from sub caliber (sabot 223) to "very heavy" (for cartridge) projectiles, the OALs will be all over the place. The twist rate should be considered when choosing a projectile for a 30-06.
But once again, the actions lengths are usually non specific, they usually run in classes short med long. The 721 is what is generally considered long, and the 722 was manufactured shorter to accommodate shorter roundS (plural), not one specific round. SAAMI determines the chamber length, and the cartridge length (civilian US), CIP does this in europe.
You have heard of the Winchester super short magnum? They designed that action specifically for that cartridge as none other known has the same requirements. You may find commercial actions with magazines too short for some types of current factory ammo because when the rifle was produced, round nosed bullets were the standard type and therefore were shorter overall.
I certainly have heard of the SSM WIN s, and as I posted "Actions are seldom designed around one [cartridge]", I did not say never!!!!!!! However, we should read the entire thread, then we would be able to stick to the 721-30-06. Did Remington base its magazine length and chamber length based on measuring the magazines of other rifles? I believe only a dreamer would believe this is so.
I'm also aware of a at least one AR manufacturer that chambers for the wssm!!!! They did this without changing the lower receiver size!
The 721 came chambered for the 30-06, but also for the 300 H&H,SAAMI specs call for max length for each 3.340 inches and 3.600 inches! From the same action!
Head-space is the distance between the bolt face to the DATUM LINE on the shoulder of the chamber. (rifle cartridges). The datum line is a specific point where the case shoulder meets the shoulder of the chamber. Thought this would be useful to know what the datum line is.