Kel-Tec SUB-2000 can be ordered with 4 mag types:
. . Glock (17 or 19), S&W Model 59, Berreta 92, or Sig Sauer P226.
.40 S&W versions
. . Glock 22, S&W Model 4006, Beretta 96, or Sig Sauer P226.
My understanding on the Glock 19 version is just a Glock 17 version with the pistol grip hacksawed shorter to fit the shorter mag (Here-say so don't take it as gospel), but that is also why I just ordered the Glock 17 model. I have used 17, 19, and 33 round mags with my SUB-2000 (and my Glock 26 for that matter) and have had no problems whatsoever.
I have my Maverick 12 ga for HD, the SUB-2000 is a plinker/SHTF/camping carbine.