Ar308 build

[Garron]

Hey all I need some guidance 

I just finished an ar308 build and I'm having pressure issues I'm using a Criterion barrel (m110 contour) 20in. Rifle length gas system and a ADK bolt... Bolt and chamber ext. DPMS compatible. I've got about 40 rounds through it. I started with some hand loads that 42.8 grains of varget fed brass and 175gr. Berger otm tactical bullets at 2.80 col I got ejector pin marks and cratered primers so I decided to use factory ammo and I used federal gold medal match 168gr at 2.80 in still got cratered primers and very slight ejector pin marks. I realize these are signs of over pressure but with fgmm 168's this shouldn't be happening do you have any ideas you can send my way .... Could this be a headspace issue...... Confused!!!!

[392heminut]

Deleted

Edited November 21, 2016 by 392heminut

[shepp]

Welcome to the forum 

[jtallen83]

Welcome from Iowa, via Pensacola!

I see those issues regularly with M118LR and FGMM 175 gr 7.62, doesn't bother me. I chalked it up to the firing pin hole being a touch oversized or the pin undersized and then being a touch oversized on the gas port with the heavier loads.

Edited November 20, 2016 by jtallen83

[survivalshop]

  How about some photo's of the spent Brass .

[Garron]

will get some pics of brass but it's opening day here in western NC.

[Garron]

Pic 1 42.2 gr Varget pic 2 a 168gr fgmm 

[survivalshop]

  I think Jtallen83 is correct about the Bolts firing pin hole , it may be too large . You see a lot of this same issue with the new DPMS GII rifle , seems like they all do it . Primers don't look flattened , so its probably not high pressure sign .

 The Powder charge is with in load spec's , what is the COL of you hand loads , but if factory fodder is doing the same thing , its not your hand loads .

   

[98Z5V]

Brass looks fine.  You're gonna see an ejector swipe on almost every round. Those in your pics aren't a problem.