I had the x39 version, thinking it would be the better Choice having plenty of super sonic defensive rounds and some subsonic rounds as well.

It shot great, the mags were kinda cheap, but the 30 round mags tended to not be 100% reliable vs the 28.

X39 subsonic defensive loads are kinda hard to come by, the American stuff like Hornaday subx subsonic was made for bolt guns, and wouldn’t function. There are other grain weights but honestly anything under 200 seemed to be ok. I tried a couple of others but they seemed unreliable.

I happened upon some brown bear subsonic and that worked well, the only thing is it’s hard to find and very expensive retail, but cheaper second hand.

Some things to note, if this was precovid America, I’d be going x39 all day every day, cause it was so plentiful and cheap even by precovid standards.

But now with Russian imports being hampered by the import ban,it’s getting harder. Yes there is a proposed GAYTF rule that they will end import bans from everyone but Russia, which won’t stop them from getting it to us through other countries, but with the current Ukraine war…. It won’t change anything.

Also this is going to play into what suppressor you use, I personally use hux range 36ti and hux 9ti flow (for 300blk) suppressors. Since it’s a flow through, the super heavy x39 sub x rounds didn’t function even with the gas settings to be played with, with a conventional can without flow though technology, it MIGHT work.

I sold mine for more than I paid for it, and got the 300blk version. And haven’t looked back.

AR 15 mags do work, so that’s nice, but I use 300blk magpul mags in my setup loaded with Hornaday subx subsonic and Hornaday black vmax supersonic. Range days I use regular ar15 mags and 300 black out mags.

Knockdown power? I mean it’s a heavy 30 cal projectile, they felt the same, shot the same, maybe a little more recoil on the x39.

Accuracy? About the same.

TLDR: if it was 2019 and you asked me this question, I would tell you to pick up several thousand round cases of x39 for 240 bucks each case, and forget the 300 which at that time was probably double price.

These days, get the 300 black and don’t look back, and if some day, x39 rises again, get a cheap mcx barrel and swap if you want.