Need help with 300 Blackout and Round Nose Bullets

[reynolds25]

I have some Sierra 220 gr round nose bullets and would like to load subsonic rounds for my blackout AR. I have heard of feeding issues with these bullets in the AR platform. Does anyone have experience with getting these bullets to feed in an AR and what was your cartridge overall length? I have seen mixed COLs in my online searches.

 

[Winterborn]

I've tried to use round nose subsonics (220gr) bullets in my 300 blackout, but they will not feed reliably. Even manually charging them they tend to stovepipe half the time.

My 300 has the extended feed ramps, didn't make a difference.

YMMV

 

[reynolds25]

Update- I loaded them to multiple COLs and they all fed from Magpul magazines. The would not feed from GI mags. I could barely get the rounds out of GI mags by hand. If you have Magpul mags this can be done!

 

[Winterborn]

Update- I loaded them to multiple COLs and they all fed from Magpul magazines. The would not feed from GI mags. I could barely get the rounds out of GI mags by hand. If you have Magpul mags this can be done!

Its funny, but 30rd Magpul mags and my Blackout hate each other....

However, 20rd Pmags and the GI steel mags work great.

Oh well each gun is different.

 

[IndispensableDestiny]

I know these are desperate times with components, but I do not believe that bullet was intended to be fed from a semi-automatic action.