As does a converted AR to 7.62x39
No, not really. The tapered case of the 7.62X39 doesn't lend itself to being forced through the straight, deep mag well of the AR pattern rifles. There's a reason that the AK mag has that constant curve.
I know Colt built AR's in that chambering for a couple of years, as did a couple of other companies. Colt doesn't make them anymore and neither do any other top tier manufacturers. There's a reason for that.
I know that some people have gotten them to run, but I see those as range toys, not something that I would ever consider reliable enough for defensive purposes. I'm obviously not the only one.
If a 7.62X39 AR was a viable proposition, LMT, Noveske and others would be making them and someone other C Products would be making mags.
300 BLK exists for a reason.
I have shot the 7.62x39 in AR's with no problem, none at all and have several customers that use it as well with no issues. Most companies stopped making it due to the surplus ammo not being so surplus anymore unless they made up the reason to cover up reliability issues.
Basing whether or not its viable because a couple manufacturers don't make it doesn't make sense. When it was produced it was fine, there is a reason they sold so many barrels and why they made it as long as they did. If it wasn't reliable they wouldn't have marketed it and sold as many as they did.
300BLK exists because the military asked for it, the concept has been around for years and years and years in various incantations and all the manufacturers never touched it until it went SAAMI and was backed because of the military request. If Remington didn't push it through SAAMI and the military didn't ask for it it would still be 300Whisper(TM) or 300-221. All those shops could have ran with the 300-221 if they wanted but noone was doing it; it wasn't popular and there was no bandwagon to hop on. Alot more of this industry runs on whether or not a buck can be made over the reliability or viability of said product.
It's a more ideal cartridge for the AR platforms(300BLK) because there is less work needed to get it to run right.
I am just blown away at how many people are head over heals for this cartridge when noone seemed to care much while it was a Whisper(TM). I never thought it would gain the following it has since the concept and the original cartridge has been around for awhile.
95% of the guns anyone talks about here are range toys, and nothing more. The possibility of unreliability for the cartridge drives you away from it.....so don't buy one then. My experience is that it is reliable and I would defend the homestead with the ones I have shot.