Impact on accuracy with headspace too long

[justinp61]

I'd never consider using brass that is .002" longer than my chamber in any rifle. It only takes a few minutes to run it through a sizing die, problem solved.

 

[bobcat93]

Is it Lake City?..thick 556 brass..
A lot of that brass is sold in bulk..its nice stuff..but!...
I'm told by the boys in green, when you see a lot of that brass for sale it was probably S.A.W ammo..
If you think about it..the light will " C.L.I.C.K.:!...
Hahaha...
One problem with surplus brass when shot from auto weapons is its ripped out of the action while the chamber pressure is still high..the reward motion of the bolt opening cause the brass to be stretched much more then a bolt action, or semi auto .
Thats one of the reasons when sizing 556 brass there is so much to trim off...
Its thick stubborn brass...
Deprime 5 cases and full length size bump that shoulder back..
Aneal the case..full length size do not pull case out of press..lift ram a little..spin case 1/2 turn, size again
See if it needs alot trimmed off..
Once fired brass is very springy ..especially stretch out saw brass...

Make up a few dummy rounds and see if the bolt locks shut...if it does..you have a lot of work to salvage the brass...
I bought a lot of 5000pc ..it took me all winter to prep and sort..I had problems..but I learned a ot about what it takes to salvage that brass and make it up to our specs..so we can use it..
By the te I was finished I said..never again..ill just pay for Lapua brass and be done with it....
Just a thought...

 

[bobcat93]

I ended up building this to correct the issue

 

[DR_2297]

The AR will eat it if you send the bolt home under buffer spring pressure. Easing it forward you may or may not have issues. As far as precision - you will be forcing the case head and shoulder into chamber space and that may create misalignment of bullet into freebore. So you may end up with some erratic performance. Maybe not…

If it was me and I was using this stuff in matches, especially big / important matches I would be setting them back to .002 under zero. Zero being whatever zero is with my comparator set to zero on a Go headspace gauge. That is pretty much my standard when sizing brass as when I chamber my barrels I set headspace at +0 to +.002.

 

[jelenko]

Is it Lake City?..thick 556 brass..
A lot of that brass is sold in bulk..its nice stuff..but!...
I'm told by the boys in green, when you see a lot of that brass for sale it was probably S.A.W ammo..
If you think about it..the light will " C.L.I.C.K.:!...
Hahaha...
One problem with surplus brass when shot from auto weapons is its ripped out of the action while the chamber pressure is still high..the reward motion of the bolt opening cause the brass to be stretched much more then a bolt action, or semi auto .
Thats one of the reasons when sizing 556 brass there is so much to trim off...
Its thick stubborn brass...
Deprime 5 cases and full length size bump that shoulder back..
Aneal the case..full length size do not pull case out of press..lift ram a little..spin case 1/2 turn, size again
See if it needs alot trimmed off..
Once fired brass is very springy ..especially stretch out saw brass...

Make up a few dummy rounds and see if the bolt locks shut...if it does..you have a lot of work to salvage the brass...
I bought a lot of 5000pc ..it took me all winter to prep and sort..I had problems..but I learned a ot about what it takes to salvage that brass and make it up to our specs..so we can use it..
By the te I was finished I said..never again..ill just pay for Lapua brass and be done with it....
Just a thought...

Again, thanks for the ideas! The brass in question has been fired and resized 6 times by me. It's just this time the third party didn't resize the cases properly. He and I have already discussed and he knows what went wrong in his process.

 

[jelenko]

The AR will eat it if you send the bolt home under buffer spring pressure. Easing it forward you may or may not have issues. As far as precision - you will be forcing the case head and shoulder into chamber space and that may create misalignment of bullet into freebore. So you may end up with some erratic performance. Maybe not…

If it was me and I was using this stuff in matches, especially big / important matches I would be setting them back to .002 under zero. Zero being whatever zero is with my comparator set to zero on a Go headspace gauge. That is pretty much my standard when sizing brass as when I chamber my barrels I set headspace at +0 to +.002.

Right. I'm using these only for practice.

Good point on potential run out. I'll build 20 or so rounds; measure run out; cycle them with a ground off firing pin and remeasure run out.

 

[DR_2297]

Right. I'm using these only for practice.

Good point on potential run out. I'll build 20 or so rounds; measure run out; cycle them with a ground off firing pin and remeasure run out.

Nothing is ever perfectly coaxial or concentric. Brass has spring back, expander buttons cause straightness issues, the list is endless and most ppl don’t have the tools to measure or knowledge to understand what they are measuring. Freebore to bullet diameter is a close fit. With mag length ammo you really aren’t in the freebore. So if you pinch the case between bolt and shoulder and deform case to fit you may or may not present the bullet on an angle to the bore. On the other hand it’s really a crap shoot when you have a properly sized case and depend on the ejector to hold case against shoulder and have that concentric to bore. We all take this stuff on faith and hope that the barrel isn’t finicky. But output threshold Thst we accept is totally dependent on end goal on target.

 

[bobcat93]

Yes..what they said

 

[jelenko]

Nothing is ever perfectly coaxial or concentric. Brass has spring back, expander buttons cause straightness issues, the list is endless and most ppl don’t have the tools to measure or knowledge to understand what they are measuring. Freebore to bullet diameter is a close fit. With mag length ammo you really aren’t in the freebore. So if you pinch the case between bolt and shoulder and deform case to fit you may or may not present the bullet on an angle to the bore. On the other hand it’s really a crap shoot when you have a properly sized case and depend on the ejector to hold case against shoulder and have that concentric to bore. We all take this stuff on faith and hope that the barrel isn’t finicky. But output threshold Thst we accept is totally dependent on end goal on target.

Hmm. So, doesn't make sense to check run out before/after chambering?

As you mention, what we do depends on the level of accuracy needed => this is for 'cross the course' => +/- a tenth or two in group size doesn't matter. The load with unmolested rounds is < ,75 MOA [at least over several 5 shot groups.]

 

[Gargoyle]

I had a friend make me some ammo when I didn't have time. Gave him 77gr SMKs, LC brass, WSR primers, and H4895. (24gr per case) About 100 cases out of the batch would chamber, shoot, and accurate. The only problem was when I tried to eject a loaded round. I had to use a rubber mallet or my heel on the charging handle. He used walnut media on that batch to clean the cases, and the rest corncob so the look of the brass could tell me which batch he sized too long. I eventually shot them all, but only at the range, not hunting. Maybe this story helps...lol.

 

[Coyotefurharvester]

Would be totally unusable for me, when hunting in the winter. I want ammo to load without FA, and only about 1/2-2/3 bolt travel required.