Bullet concentricity and the AR

[texdoug1]

I have an AR in 6.5G that I am absolutely queer for. I've reloaded every round that has ever been through it, and was wondering a while back if concentricity was effecting my loads so I bought the Hornady gauge. Keep in mind I'm using Lee equipment. 123Amax seated great, but my average 120NBT was .006 out. So I fixed a couple to less than .001. I loaded them in a mag and cycled it manually. When I extracted them they were both out .004 just from cycling. Is this just to be expected from an AR? I realize that the cycling action is pretty violent, but I wasn't expecting that.

Sorry I know I ramble.

 

[Playerz1337]

Re: Bullet concentricity and the AR

I'm not sure if it would be worth polishing the feed ramps, that would make for a little less friction on the bullets.

I don't think there would be much else to help keep the bullets seated unless you started crimping them.

 

[MALLARD]

Re: Bullet concentricity and the AR

the ejector pushes the case to one side... upon extraction your going to see that effect the runout of lounded rounds that you extract, i believe.

 

[texdoug1]

Re: Bullet concentricity and the AR

Great point Mallard. I never thought of that.

 

[texdoug1]

Re: Bullet concentricity and the AR

Would removing the ejector and doing the same thing give me more realistic results?

 

[X-fan]

Re: Bullet concentricity and the AR

If you performed accuracy tests between perfectly straight rounds and those that measured 6 thou you couldn't tell the difference.
Fugget about it.

 

[texdoug1]

Re: Bullet concentricity and the AR

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: X-fan</div><div class="ubbcode-body">If you performed accuracy tests between perfectly straight rounds and those that measured 6 thou you couldn't tell the difference.
Fugget about it.

</div></div>

OK. I read in multiple places that .006 out would lead to 1in+ groups by themselves.

 

[X-fan]

Re: Bullet concentricity and the AR

ER...That would be incorrect.
Spin some match grade factory ammo and you will see what I mean.

I have some 800grain 50 cal bullets that have almost as much as 0.004 runout IN THE BULLET with a 0.001 wobble in the middle...The loaded rounds were running up to 0.010 total runout.
I recently shot an 8 inch 1000 yard group with them!

I have a 6mmbr that shoots 0.10-0.20 groups when I do my part and I am am not sure if I could see 0.005 with that rifle.