This is something I'd expect to see on YouTube shorts being fired at an indoor range by a swarthy gentleman as he puts multiple rounds into the range's ceiling (except for the suppressor because those people can't pass background checks).
ARs chambered in 5.56 should really have barrels no shorter than 10.3" long. Under that, and you've basically got a flashbang garbage rod that beats itself to death due to the amount of gas being pumped back into the upper to make sure the gun cycles reliably. Even 10.3"/10.5" isn't great. The Mk18 was always a compromise. 11.5" is the best shorty 5.56 length, imho. 11.5" has ~40% more dwell time than 10.3", which results in slower internal parts wear and lower likelihood of malfunctions.
A big problem with all the cheap AR "pistols" out there is that they all use utterly gaped gas ports. The CRANE spec gas port size for a 10.3" barrel is .070. I've seen PSA and Aero 10.5" barrels' gas ports pin gauged everywhere from .078 to .086! Those guns will obliterate gas rings and extractor and ejector springs insanely fast. Never mind that these cheapo shorty ARs usually ship with a standard carbine buffer spring and buffer, making them ridiculously harsh recoiling for 5.56.
AR barrels under 10.3" should only ever be chambered in .300 BLK, quite frankly.
