FTF On Grendel Suggestions

[zzrguy]

I'm haven a simular issue with my Grendel I just installed a adjustable gas block hopen it fixed it I'll know Tuesday

[BCHunter]

What are the components of the lower? Buffer weight and spring ? Have you chronoed the factory vs reloads? That would help determine under gas or over gassed. I would bet it is on the under gased side, your reloads a bit slower then the factory load, and the buffer spring is faster then the mag spring. So heavier buffer, or different mag.

[grayfox]

Another thought... full bcg backward travel can be inhibited by new parts not broken in against each other... IDK but you'd get a weak eject then not fully cycled back to fully pick up the next one, so it slides over... kind of short-cycles.
I had one 18"-er that I had to basically feed single feed for the first 40-50 rounds... tried several things but part of it I'm sure was all the new parts being stiff, after breaking in and loosening up they worked better.
I recommend always break in with factory ammo like Hornady 123 Black or Hornady AG123's or the Federal 90's, not too expensive and you have one variable removed from the equation.
$0.02 to consider...

[LRRPF52]

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

[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.

[m1a convert]

ISSUE SOLVED

I used a standard Carbine spring with a Spikes Tactical Heavy Buffer in both guns. I shot 300 rounds with one feeding issue that was from a different issue. It fed the FMJ and the Hornady Black great.

Thanks guys.

[LRRPF52]

ISSUE SOLVED

I used a standard Carbine spring with a Spikes Tactical Heavy Buffer in both guns. I shot 300 rounds with one feeding issue that was from a different issue. It fed the FMJ and the Hornady Black great.

Thanks guys.

Did you meant to post this in your thread? This is Gos's thread where he's having bolt over base malfunctions.

[Gos]

Well, obviously I set this aside for a while, but came back at it again last month.
Problem solved; completely.
I took off the JSE Barrel and replaced it with a Faxon barrel.
Now on to other things.