My 10.5" I put a LPVO on it to see how accurate it was with 75gr bullets. It shot just under MOA. So I put on a Swampfox Blade 1x25. At 50yds with it its about 2 MOA. Definitely my fault but it's good enough for what it's for.
I suppose they would be better chambered in 300 blackout
Love the AR in your photo! Is that a 50 or 60 round magazine? Does the muzzle blast beat the crap out of the weapon light? Good luck & stay safe!
I think what others have posted gives you a lot of good feedback, and the velocity data posted by DadSmith is very revealing. Generally, the M855 and M193 bullets are not reliably lethal below 2,500fps. Some operators do go to 300 AAC Blackout to gain more terminal energy using SBR and Pistol length guns. FYI, in my experience, as a Police Officer having available an .223/5.56 SBR as a Patrol Rifle, the shorter the overall length the easier the gun is to maneuver inside of or exiting from a vehicle, as well as being able to turn around within a home's narrow hallway (especially a mobile home) keeping the gun up in case threats need to be engaged. My own limited experience with a 7.5" barrel + blast can is that it was just too darn unpleasant to shoot, and even more unpleasant for team members. If a Suppressor is not to be used, then I am most happy with a 10.5" barrel + a ~3" blast can (the weight of a Suppressor can be a handicap). Realistically, good .223/5.56 ammo is a lot easier to come by than 300 AAC Blackout, although just about any centerfire round within a 50m distance is going to hurt. You pays your money and takes your choice. Good luck & stay safe!
I love the humor and truth in your posting! Thanx!
