I bought one of these at the beginning of the ammo crunch when I realized I missed the 300BLK/5.56 ammo train but commie-x-39 wasn't drying up or climbing $$ at the same rate. I was leery at first & ready to flip it if it was a dog.
It helped that it was a very good fit & replace a 300BLK & transition directly over to a hog thumper with no weird boutique equipment to source or major machine work most AKs take to match capabilities of an AR.
The DI gas system has a noticeably less aggressive recoil impulse that any of the piston guns I own in that caliber. Adding a can helped it even more & it suppresses way better than any AK. I've seen some custom build x39 ARs run reliably across those conditions but none of the rattle box x39 ARs have ever managed to do that.
For under $250 I swapped out the standard M4 stock, grip & GI trigger that comes on the Resolute 100 series rifle with a CMMG ambi safety, LaRue trigger, Magpul MOE stock, & a griffin taper mount muzzle device to make my poor's version of a 300 series rifle minus a fancy finish.
Out of the box accuracy with Wolf Polyperfomance & lacquer case HP or FMJ was surprisingly under 1.5" with 5 shot groups @ 100yds using a 4x day optic. Moving over to imported SP ammo from a couple manufacturers it opened up to around 2.5"
IF these were available at retail price they'd be a very good choice for anyone wanting to ditch 300blk or provide some caliber diversity to their collection with a reliable and well performing x39 platform.
It proved itself to me well enough that I also bought a pistol version that I dedicated one of my ancient direct thread cans to. #nopigsmatter