Not to be a butt, but the "recommended ammo" is a bunch of hooey and/or much ado of nothing". Most any semi-automatic firearm will have ammo that it likes and doesn't like. You can run or attempt to run, any standard pressure commercially manufacturer ammo without harming the firearm. Their (S&W) intent in stating some ammo as "not recommended" is to buffer the fact that 22 rimfire semi-automatics have always been notorious for not running. Possibly they had reports sent in with returned rifles saying "this" ammo won't run.. Most likely it was the result of a back and forth with disgruntled owners. Do I believe that S&W researched all the different brands of ammo to find what would or would not run, not for a minute.

So, what to do.. You got to start somewhere, so pick something with a good rep and buy a box or two. If it runs, well then you know one that does. Expand from there as much as you like with others. It's all much the same as defensive round verification in a carry pistol.

Reading the "included with firearm" manual is often over-rated. Best to learn how a specific firearm functions and go from there. I wouldn't worry too much about voiding a warranty while doing standard stuff either. It's all just CYA on the part of the manufacturer.

For the M&P I started with CCI Tactical.. No reason other than it was CCI and sounded interesting. It runs just fine. Next I tried some Winchester M-22, it also ran fine. Both run fine in my MKIII's as well. If I can't find those for some reason, I'll try something else. It's not really a big deal..

Just my opinion.. Ron