Take 98Z5V's advise and ditch that gimmicky buffer setup. Get this and never look back: https://www.armalite.com/SACItem.aspx?Item=AR10REKIT01&ReturnURL=/Armalite/Product-Category/AR10-Parts-Accessories/Lower-Receiver-Parts&Category=ac614400-ff09-4cdf-9d35-419a654e7201
When I put together my Aero M5 I just used an Aero M5 lower parts kit. I had zero issues with the bolt not locking back with their bolt catch. I did stray from their DPMS 308 buffer tube, spring, and buffer set up though. I went with an Armalite AR10 kit. Again, zero issues.
The good: Ambidextrous controls, lightweight, uses DPMS low pattern handguards, Armalite length receiver extension, somewhat inexpensive.
The bad: S&W decided to makes the bolt, carrier, and barrel extension proprietary. One can swap out the barrel and BCG with any DPMS compatible parts they like once they wear out the original barrel though.
I bought it so that there would be more of the mag release button protruding. Aero Precision solves the problem of a short mag release by selling an extra long button. I had the same problem with my MATEN. I didnt have a problem with it not holding the mags in though.