Hi all,

A few years ago my family bought my brother a RRA LAR-8 for graduation. Gun has always been a little bit of a pill for one reason or another. It shoots well, though... when it shoots. It has a RRA 2-stage trigger. Everything on it (except optics/mount) is factory.

Currently the issue is very random light primer strikes. Happening on hand loads and on various factory ammo. Happens only occasionally; gun will fire multiple rounds before it decides to have a light strike. After a light strike, I can usually (always?) reload the round and it fires just fine.

What is the list of things to check to try to resolve light primer strikes? Trigger/hammer spring? What else?

Planning to call RRA next week sometime.

Thanks.

I'd try a heavier hammer spring. Are you sure it's fully in battery?

Thanks, any others?

I think Cowboy covered it pretty well. If it's always fully going into battery I would suspect the hammer spring. Two other things you can check. Make sure your firing pin looks good. Some .308 AR's have firing pin springs and some do not. I'm not sure on the RRA. If it does, replace that.

Earl

Thanks. RRA LAR-8 does not have a firing pin spring; it functions just like an AR-15 BCG.

I'm 99.9% it was in full battery every time it had a light strike. The .1% uncertainty is because I was not checking before every shot.

Measure the firing pin length and then compare to two or three standard "mil-spec" firing pins from your other guns or friends guns.

If yours is on the smaller size end of the scale swap it out with the longest and give that a try for awhile.

Thousands of an inch matter on firing pins, could just be you got a small one...

I would clean the chamber to make sure there is no trash anywhere. Then take the bolt apart and clean it. Too much lubrication on the firing pin can trap debris. If all that cleans up and looks okay I would check headspace just to be safe. Have you ever had a suppressor on it?

Is it always with the same ammo, some 7.62 surplus has harder than normal primers and needs a heavier hammer strike to ignite.

Thanks all.

It does it with different types of ammo. Never had a suppressor on it.

Make sure the trigger spring is installed the right way

You'll get a harder strike if you cut the tail of the hammer off like this



KE = 1/2 * m * v^2

This doesn't affect the disconnector or anything else functional. The tail on the hammer is there because that's where the full/burst disconnector is on a milspec trigger. it doesn't need to be there.