1) I don't own an M&P. Sorry for that. Not that it matters, my XD eats 180 gr cast bullets like popcorn. I can think of no reason your M&P wouldn't as well.
2) The 20 gr increase over the more "normal" 180 gr bullets found in the .40 S&W, is unlikely to factor in that much. The extra weight makes the math used for energy numbers seem more impressive. Where SD is concerned, bigger problem to me is the fact that it's a cast bullet. If you read the product description on the Double Tap web site, it's for "... for woods and hunting applications." Great for things with teeth and claws, a bit too much penetration perhaps (IMHO) for your typical human. For long walks in the woods, they're probably great. For the mall parking garage after dark, normal SD hollow points are a better choice.
MSgt, USAF, Retired
NRA Life Member
Liberals are constantly telling us about the poor and oppressed in this country. With that in mind, why do they feel the need to keep importing poor people from other countries?