Old gun----new problem....Solution on Page 3

[davidj]

Well, your extractor works!

Load is clearly too much for your system, so back down. You should also look into a heavier buffer. Did you say you have a RRA "CAR" complete lower? Like with a telescoping stock?

If so, you probably have a 2.9 oz buffer. While they work with a lot of carbines and factory ammo, I only use H2 and H3 buffer weights, considering pushing 123gr bullets.

The military buffer, recoil spring, gas port, dwell time, and bolt carriers are meant to push 55gr-62gr pills at high pressure, and they use a bolt carrier that is heavier than the RRA AR15 carriers. That gas ports are cut to offer reliable operation across the temperature range.

Was your recoil spring used in a 5.56 gun before going Grendel, and if so, for how many rounds? They need to be replaced once a certain round count or minimum length has been breached.

I bought the RRA carbine lower (6 position telescoping stock) new about 400 rounds ago. The buffer does indeed weigh 2.9 oz. Question now is H2 or H3