I shot first few hundred rounds through the new gen 3 sub 2k the other day at the range.
All 124 grain magtech FMJ. With the Glock mags, both 15 and 33 round, the carbine functioned flawlessly. The 30 and 40 round ETS sticks gave me some failures to feed correctly. These aren’t everyone’s favorite mags but had so far functioned perfectly on my old gen 2 sub 2ks as well as my AR9. I didn’t try my drum mag yet, but it could be this iteration, or this copy, is a bit more mag sensitive.
Regardless, she’s a keeper.