Question 300 AAC Blackout and 223 lower

[cms1528]

Can you mount a 300 Blackout complete upper to a standard AR15 223 lower. I did a search on this forum and did not see any info. Its seems to me that it will as long as the barrel is chambered for 300 AAC type rounds.

Also, do the 223 mags hold the 300 Blackout rounds without any modification. Thanks for the assistance.

 

[JailHouseLiar]

Can you mount a 300 Blackout complete upper to a standard AR15 223 lower. I did a search on this forum and did not see any info. Its seems to me that it will as long as the barrel is chambered for 300 AAC type rounds.

Also, do the 223 mags hold the 300 Blackout rounds without any modification. Thanks for the assistance.

Yes, you are GTG . . . and have fun! Don't get the ammo confused. You understand what happens if you do I trust.

 

[ar450]

Yes and yes.

 

[dungslinger]

I am getting different color Pmags to combat the ammo issue. I just need to find the ammo now.

 

[cms1528]

Thanks, I may built a pistol in 300 AAC. From what I understand the 20 round pmags work flawlessly. A concern of mine was the the location of the 300 round's shoulder in relationship to the mag ramp. Thanks again.

 

[Sticky]

I have been running a 30rd pmag on my 300 pistol, no issues here..

 

[fidelity]

Sorry for the slight tangent, but these pistols look like fun builds, and I have too many lowers (that I probably would have bought a year or two from now had it not been for SB281 - so I'm learning new things quick).

Are there features that one needs to be careful about (e.g. no AR shoulder stock or forward grip) so these qualify as a pistol and not an SBR?

I presume an attraction of the 300 Blackout cartridge in a pistol is the larger bullet size than a 223 round? Does this also mean (with less shell space due to the bigger bullet) the powder is finished more quickly and one doesn't lose much in the shorter barrel? A nice flash suppressor is probably a must.

 

[BradMacc82]

Sorry for the slight tangent, but these pistols look like fun builds, and I have too many lowers (that I probably would have bought a year or two from now had it not been for SB281 - so I'm learning new things quick).

Are there features that one needs to be careful about (e.g. no AR shoulder stock or forward grip) so these qualify as a pistol and not an SBR?

I presume an attraction of the 300 Blackout cartridge in a pistol is the larger bullet size than a 223 round? Does this also mean (with less shell space due to the bigger bullet) the powder is finished more quickly and one doesn't lose much in the shorter barrel? A nice flash suppressor is probably a must.

As long as your over 26.5" OAL (I believe, don't take it as gospel yet), you can run a vert. grip and be legal. If your under that length, then no VFG, but you can use the Magpul AFG, since it's not a vert. grip as per the BATFE. And no shoulder stock whatsoever on pistol builds.

Big attraction of the 300BLK is the added energy and it's efficiency in shorter barrels when compared to 5.56, it also suppresses really well too.

I've had 2 myself, a 16" for hunting, and a 12.2" for those "bump in the night" moments. It's a niche round, but for it's niche it performs well.

 

[fidelity]

Thanks for the follow up. Glad that I bought more than a few lowers.