Recent manufacture M&P 9 accuracy

[OldState]

I think for "scientific" purposes the test firings should be bench rested or in a mechanical rest if possible. The ammo should be similar too...but definitely rested. No offense, but the above pics are only usefull if your capable of shooting 9mm groups at 25 yards

Someone here said the external dementions of the the 40, 9, and 357 are similar and when comparing the muzzles of all the calibers, the 45 in the thinnest bore. The are also supposed to be the most accurate.

I wonder if the 45 is the least heavy barrel and if barrel weight (compared to the recoil aspects of the particular cartridge) is the key component affecting accuracy in this design.