As noted,, despite the appearance of being identical,, they are different machines. As such,, the cheapest & easiest thing is to play with reloads.
As noted,, sometimes a single load works well in many different guns,, while some loads never work but in one gun.
Your post left out a lot of info.
Factory ammo or reloads?
Cast or jacketed?
If cast,, have you slugged the bore?
Thread choke issues? Have you checked for that?
And as noted above,, who & how were the cylinders reamed?