If you’ve never heard of QC10, you have completely ignored the PCC movement over the last decade.
QC10 is the company that picked up the pieces of the defunct DDLES company. The owner was stripped of all rights to the receiver design and was outed over embezzlement.
QC10 was the main company pushing the Glock mag design.
If configured correctly, as in buffer and spring, it’s a soft push type of recoil, and it’s not gassy.
Many people build guns these days with crap Chinese parts and poor instruction.
This right here ^^^
I think that Quarter Circle 10 and Angstadt Arms are the two premier AR platform pistol caliber carbine manufacturers in the USA.
Designed from the ground up for pistol cartridges, no adapted parts.
Angstadt if you like Glock pattern and QC10 if you want more options.
Personally, I don't like the mag at the "Glock grip angle" (purely aesthetic) so I got the Colt pattern which uses a modified Uzi mag that is 90 degrees to the receiver.
No mag cost penalty, about the same cost as the Glock 33rd. Metalform and Brownell's are both reliable mags in my QC 10 Colt pattern.
My QC-10 did not like C-Products Defense mags.