As Miller alludes, recoil will cause the gun to rotate laterally in the direction of the barrel being fired, resulting in the payload to exit the barrel after movement and hopefully pointed at the target.
I'm seeing about .011-.013 convergence on my 410s. I would expect to see that on all 410s that hit correctly. Some may have to be swamped to get the latter part of the barrels to that convergence.
If you look at the muzzles on the 410 CSM OO frame Repro barrels for 28g, you see they are about 1/8" apart. No doubt to get to the right convergence
without swamping.
http://parkerguns.org/forums/showthread.php?t=5889
