You will have to modify the Slide stock to fit your trigger lower guard. The M&P lower trigger guard swing low and the stock plastic hits it. Most AR's have a flat aluminum lower guard plate. Got to see one on an AR15.. Now just my opinion, I don't like them for the fact the control-a-bility is iffy due to the bump fire design, you can't use your optics or even your iron sights, just hold up pull in with your weak arm, and she rocks until empty... My question aside from the FUN FACTOR, why?.. Just my opinion so nobody get their undies in a knot.. I give the guys an A for creativity for sure..
As far as the M&P able to handle the full automatic fire, well you can update us on that part. I don't know if S&W designed the M&P 15/22 to be fired full auto, but with that said, the design is solid and strong enough to be able to maybe handle the volume. Drop a line to S&W at their web site "Contact Us", ask them and see what they say.. Update us with the results. I'm sure others (in states where you can have full auto) would love to hear the results. Here in Commifornia, we just dream about that function...
