Yes it did, but you are limited to either 16 or 20 round mags I think. I built one for mine so I could run the higher capacity unmodified 30 round Grease Gun mags. with a different mag catch I could run run larger cap 50 round Mac- 10 mags. I haven't used Mac-10 mags though, the Grease Gun 30's are enough for me. And these mags are tough! Could practicaly hammer nails with'em.
+1 the grease gun conversion rocks. Plus You can use the mags themselves as weapons