Home Forums Hunting & Shooting Ask The Gunwriters 308 165 GMX superformance ammo

A friend of ours brought a SOCOM M1A over cause he was having trouble getting it zeroed. He brought an unopened box of this stuff to zero the gun. I shot it at 15 yrds first, just to see if we were going to be on paper..we were, but the bullet hole looked out of round. Thought maybe cause the cardboard I was using was damp. Move to 50 yrds, shot two more. Now the bullet holes were definitely oblong. What`s going on? Took the empties inside, loaded them with some 150 grn corelocks I`ve got, shot em, perfectly round holes.
Twist rate, not sure, haven`t looked it up yet, but it should be between 10 and 12, enough to stableize a 168 grn MK. I don`t shoot factory stuff.

Any thoughts?

Thanks

Yea, one source says 1x10 the other says 1x11..

Told my friend to get some Fed. blue box, or Rem 150 corelocks.
Would like to know the reason for stability problems tho.

What elevation and temperature?

It's easy to measure twist-rate with a bore-brush wrapped with enough patches to make it tight when pushed through the bore.

Hi John..we`re at 1100ft. and was 47 yesterday when I shot. Label on box claims a Vo. of 2750 fps, don`t know barrel length of course. Thinking 24". The MiA`s is 16, 1x10 or 11 twist. Gives me 8" difference. Figuring a 30 fps per inch drop in M.V. gives me about 2510fps M.V. I loaned my chrony to my son, so can`t check for certain.
Wondering if with the above "thoughts" and the longer copper 165 grn. bullet might not be the problem.
I`m going to load a box of 150`s for him in trade for whats left of the GMX box. Want to shoot some out of my 24" Mauser.

Thanks, and yes, I`ve measured many barrels that way. I did not do his tho, going from what was posted on line from the Springfield web site.