Been looking to get one of the two... I've been a long time (4 years?) fan of M&P pistols and really like them. they fit my hand well, I like the angle, and I like the trigger...
I have shot my fair of glocks too. I used them in the police academy and shot friend's glocks. I was always good with them, but I never thought they fit my hand well. so I never really cared for them
Well today I had the opportunity to try them side by side...
I have large hands. a mk23 just fits my hand. I always thought a M&P with the medium grips fit my hand well too...
at my little range session today, I shot the G21 first. I realized that with the regular backstrap (gen 4) it fit my hand real well. I was surprised because people always said it was a large gun to hold. I was good with it. nothing worth mentioning or making me a better shooter. I shot to my capabilities... I did 5 rounds of slow fire at 7 yards and it was your regular grouping. nice and tight like it should be at that distance.
Now I tried the MP45... wow... I was amazed that I realized holding the Glock 21 actually felt better for me. it filled inside my palm better and didn't feel like I had gaps in there. I was able to 'better' wrap my palm and fingers around the glock... I shot the MP45 and it felt like all my other M&P pistols. the recoil was similar to a .40
going back and forth, I did some rapid firing (shoot-reacquire target-shoot) both were within expected accuracy. Within the 7 yards at rapid fire I was able to keep the groups at around 5 inches.
going out to 25 yards, the glock hit left about 2 inches. but grouped decent... the MP45 was spot on bullseye with a slightly tigther group.
I would load both pistols get them ready to go, shoot one, then right after pickup the next one and keep shooting.
I felt like I was splitting hairs trying to decide which I preferred. I think my HUGE bias towards the M&P series didn't help either.
This is how I decided... (really splitting hairs)
Glock felt slightly lighter, it held 3 more rounds, felt like it filled my hands better, less felt recoil out of gen4 (at least for me)
MP45 looked better, I preferred the trigger and slow fire I was more accurate with it
considering more capacity is an important thing, less felt recoil is good for followups and pretty much on par accuracy with eachother, I decided against my beloved M&P series and chose the Glock 21...
I'm really sad to say I didn't choose the M&P45, but in the end it's what you feel better with. I felt better with both, but the little advantages like more capacity let me split that hair and go with the glock.
Here are the contenders