FTF On Grendel Suggestions

[NugginFutz]

This is a gas system/recoil system issue most of the time, when you have Bolt Over Base malfunctions.

It's more common on 18" MLGS AR15s.

Due to the plug dwell time, cyclic rate can be too fast for the magazine to lift the cartridges up fast enough, so the bolt slips past the cartridge, and the carrier tries to drive it forward.

You end up with bolt lug dents on the shoulder of your cartridge usually, with the cartridge beat up pretty bad.

Gotta slow the cyclic rate down somehow. Pick one or a combo of these:

Adjustable gas
Heavier buffer
Heavier spring rate for the action spring

Of the above three options, I prefer reducing gas. It softens the impulse, thus reducing felt recoil. In some cases, it even takes the heat off the family dog. Assuming the BCG is of standard weight, my opinion is that heavier buffers or springs are simply treating the symptom, not the cause.