AR 308 Short stroke

bigtigga01 · Nov 19, 2014

So i have finished my PSA 308 build which consists of:

PSA stripped upper and lower
PSA LPK
DPMS BCG, rifle buffer, & spring
BHW 20" with rifle gas system
WC gas block

So far it ran with no issues using pmc 308 ammo, but when I tried the federal m80 762 I ran into some FTF issues. A friend explained that the primer strike wasn't deep and may be caused by the round not being fully seated. I'm assuming that the federal isn't generating enough energy. What steps should I take to make this beast eat everything.?

bigfutz · Nov 23, 2014

I would start with:
1) Cartridges seating too far in (overseated vs. not fully seated) - check headspace.
2) Light hammer strike - is your trigger adjustable? Maybe need different springs.

I doubt it has anything to do with the amount of energy generated by the cartridge, since that would require it going off. Does it happen on the first round or only on subsequent rounds?

FWIW, I'm not a gunsmith, nor did I stay at a Holiday Inn Express.

bigtigga01 · Nov 23, 2014

Thanks for the reply. The problem is with the subsequent round. The initial round feeds and fires with no problem and I don't have an issue with pmc 308 ammo at all, It's just Federal m80 7.62x51. I had the headspace checked at carolina rod and gun before I took it to the range. Others suggested to oil it up real good and fight through the break in period.

rotarymike · Nov 23, 2014

Did they use .308 gauges or 7.62? What is your barrel marked as?

bigtigga01 · Nov 23, 2014

I'm not sure which one they used but the barrel is marked 308win. BHW stated that both would work with the barrel but the whole 308 vs 7.62 isn't as clear as the 223 vs 556 issue.

Dave29461 · Nov 23, 2014

The BHW barrels are cut like the .223 Wylde barrels so they are able to use .308 and 7.62x51 without a problem. I have one and have shot both without any change in accuracy. Love My BHW barrels.

bigfutz · Nov 26, 2014

Does the problem go away if you manually charge it... pull the CH all the way back and let it slam? If that fixes it, you may be right: incomplete cycle. You can also try pushing the bolt forward, directly with your finger or with the forward asssis if you have one; if it moves at all you have a problem. I'm still not sure this would be what I was chasing down for a light primer strike, but it's still good to check.

bigtigga01 · Nov 28, 2014

Yes, it will manually feed and fire just fine, but the next round would not go off. I would have to try the forward assist the next time I go to the range. I guess I just have to use pmc 308 for now until I get the round count up.

rotarymike · Nov 28, 2014

Sounds then like the bolt isn't going completely into battery.

Check the hammer top and bolt carrier underside and make sure that's perfectly smooth. If there's too much friction there, along with a less-hot round it can make the bolt have enough less energy to not make it to battery. I know that's an awkward explanation, but should at least kinda make sense.

Tigerstripe · Nov 28, 2014

too much buffer spring?

Clicker · Dec 3, 2014

I know I'm late to this party but what kind of buttstock is on this rifle? I assume a fixed A2 style since you listed the rifle buffer & spring.
Also to make sure I understand the problem you're saying if you charge the rifle with the charging handle that round will fire and cycle the gun yet the second round fails to fire and shows a light primer strike - but only with Federal ammo?
Can you drop the mag, extract the chambered unfired round then place that same round back into the chamber and charge the gun and see if that round will then fire?

bigtigga01 · Dec 8, 2014

Yes its a fixed a2 tube with magpul prs stock. Also you are correct with the issue I'm having and it's only with federal. It will fire just fine with pmc 308 in the mag. I saved the rounds that didn't fire and will try to shoot them the next time I go to the range.