There is a thread here on how glock magazines are not really compatible with AR15 frames, but we know the 300 blackout with standard AR mag works very well with the AR platform.

Question: is there any superiority of the 9x19 Luger load versus a subsonic 300 blackout? When subsonic the 300 blackout is just a little faster than the .45 acp. Since I am now into the AR platform, I would like to stay with it for my choices as much as is practical.