well, if you ask... I have tried several diff mags, metal, g.i. , synthetic, all with not probs. the gi's, I hhad to download for a few, but now i can full load them , if i wish. with the hadnguards, since they have no heat reflection inside them,imagine plastic, that close to a frying pan, mmm melty! if you go over to keltec website, you can see one guys meltdown!
but they are as easy to take down as an ar, and are easy to clean. and are robust enough for sustained aimed fire, because i have taken aimed fire, with 20 round mags, and 30 round mags with it, with no problems, no target drop off, no loss of zero, or heating bbl shift. With all the upgrades to stick on it, they will cost you about 575 or so , with tax. the stripped down version, no sling, no sling attachment, no handguards, exposed bbl, etc. are about 420 or so.
so if you get one, get it like I have there. You dont need the flash hider/muzzle surpressor, but it will deff help. i understand there is an ar one on the market that cuts 93% of the muzzle flip and flash, but they are about 50 to 75 bucks each, depending on where, you get them. that would be best, because this will wanna jump up, as I am sure the su 16 will as well, so i bought this Phantom flash hider, which works well, and is about half the cost of the other one. if i wasn't such a cheap @34sss, I would have bought the other one , though. If you look at them the almost look like a solid cylinder from the sides, until you get up close and see only 4 angled , thn cuts going up the the muzzle.