This matches my recollection of the common wisdom for stock Glocks, i.e. that the smallest of each model is the most accurate. This is reasonable. All else being equal, short barrels are always more accurate than long barrels.Iirc, the most mechanically accurate glock was (back in the gen 3/4 days) the glock 26
Of course, all else is NEVER equal.
I know I have a 21SF with a frame-mounted optics rail and it's consistently good. It's not the most accurate pistol I own. Not even close. But for its type, it's awfully good, consistently so, and easy to shoot, to boot. It lives in the living room, next to where I sit to watch TV. That should give folks an idea of how much I trust it.
As for the OP's question, I think almost no one is capable of determining the accuracy limits of a particular cartridge in normal shooting. Any apparent difference won't be due to the cartridge (assuming reasonably competent ammo) but will be entirely due to the synergy between shooter and firearm.