Consistent accuracy across a range of loads?

[Andreas]

Have anyone been able to get their M&P 9mm 4.25" model to shoot a wide range of ammo accurately? I'm sitting on a few thousand rounds of 124 FMJ reloads, and the best I can do with that ammo is 6–8" at 20 yards. My SP-01 will happily punch 3" groups with the same ammo. I've no plans to reload and can't be picky about bullet type/weight given the current shortage. I'm currently shooting at the high end of SSP Expert and can't shoot the barricade stage well enough to get the points down for Master. I tried replacing the factory barrel with a Storm Lake model, but no luck there.

[Andreas]

Crickets! I guess the take-away is that the full-size M&P 9mm is inherently ammo sensitive and can't be expected to shoot a range of bullet weights/types well.

[horseman]

Mine is terrible with anything but 147's. And it wants them at a certain speed. 125's were awful.

[FightFireJay]

My M&P Pro 5" 40 is fairly picky... But my 3" M&P Shield 40 is consistently a good shooter, go figure.

I think is has to do with barrel resonance or vibration. The shorter barrels don't seem to vibrate as much because they are stiffer (same strength with less length/leverage). Or I'm full of shit and its all in my head. I'll believe either one until I get my guns in a vice.

[RH45]

Mine is terrible with anything but 147's. And it wants them at a certain speed. 125's were awful.

That's weird, mine hates 147s&115s, but does pretty well with 125s.