Good question. They legally sell 30+ capacity magazines in most places for Glock 9mm pistols and also sell large capacity mags for other Glock pistols--I can't see why we don't see them for S&W M&Ps.
You can buy Glock compatible hi cap magazines that are interchangable within same caliber guns within the Glock line that are made in China, Korea, etc. I wonder what stops foreign manufacturers from manufacturing and selling hi cap mags for the M&Ps here?
As far as I know, the highest capacity magazines currently available for the M&P are the 17 round 9mm.
The no longer made S&W 59 and 69 series semiautomatic pistols (pretty decent guns) were availabe with 30 round magazines--you can still buy the magazines---they're a double stack set up.
When Obama was elected, I purchased a few extra hi cap magazines, although the price had gone up after the election. Some speculate that it could happen again or that they might be banned all together.
I like the 30+ high cap 9mm magazines that work in my Glock 17 as well as in the 27 model. It's just nice to shoot a while at the range w/o having to reload or swap magazines. I also like the fact that Kel-Tec's Sub-2000 foldable rifle can take those magazines--different Sub-2000 models also take other gun manufacturer's magazines. With the longer barrel on the Sub-2000, a 9mm round hits with the force of a 357 round at 50 meters.
It'd be nice to see S&W expand its offerings accordingly, but S&W has traditionally been a pretty conservative company that makes better quality guns--most of which make Kel-Tec stuff look kind of crude.
