300blk pistol question

gruntz03 · Oct 18, 2020

Fired my newly built 300blkiut ar pistol today. Cycled great but wouldn’t lock the bolt back on empty while running subs with a 220 gr bullet. Would I need a higher or lower grain sub to get the bolt back far enough to lock?
7.5 inch barrel. Ammo box says 1000fps

smokey · Oct 18, 2020

Maybe switch to a lighter buffer for subs.

John from MD · Oct 18, 2020

What kind of buffer/spring set up do you have?

outrider58 · Oct 19, 2020

Since you're shooting subs, are you planning on shooting suppressed, or just prefer the lighter impulse the subs give you?
You can go lighter with the buffer and or spring. If you plan on only shooting subs unsuppressed and you can't get it to cycle properly, you can A) open up the gas port in the barrel a little more, try a lighter Sprinkco spring, C) in the worst case scenario, buy a Nemo light buffer spring for 300Blk (I don't like these if shooting full power loads. They can beat the gun up with this light spring).

gruntz03 · Oct 19, 2020

https://www.strikeindustries.com/si-ar-spre-slick.html

I’m not real sure they make a lighter buffer. It cycles and locks back fine on normal ammo. Cycles fine on subs, just doesn’t lock back on empty. Not that big of a deal.
Right now I’m just shooting subs through it because it is a little less loud, little less recoil. Have tried to jump on the suppressor train yet though I might be pretty soon.

alucard0822 · Oct 19, 2020

gruntz03 said:
https://www.strikeindustries.com/si-ar-spre-slick.html

I’m not real sure they make a lighter buffer. It cycles and locks back fine on normal ammo. Cycles fine on subs, just doesn’t lock back on empty. Not that big of a deal.
Right now I’m just shooting subs through it because it is a little less loud, little less recoil. Have tried to jump on the suppressor train yet though I might be pretty soon.

Assuming this is after 100rds, properly aligned gas system and proper lubrication, probably the buffer setup. If that link is the buffer/tube/spring you are running ditch it, that is most likely your problem. With a standard length buffer tube, standard spring, and standard 3oz buffer the vast majority will run subs just fine.

gruntz03 · Oct 19, 2020

But I like that buffer tube.

outrider58 · Oct 19, 2020

gruntz03 said:
But I like that buffer tube.

300blk pistol question

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