The 45s, both 450 and 460, need velocity under 2200 to shoot with with a 250 grain slug. That is due to the 1 in 16 twist they used, it's just too quick. I believe both companies now have a 1 in 20 twist Gives much better accuracy at higher velocities. The vertical stringing in an encore is usually due to no headspace. Had a couple mgm barrels where there was no headspace. The case stuck out of the barrel too far. Needed to run a chamber reamer in too take out .005 as some frames are too tight. It fixes the stringing. Sometimes they cut barrels to a tight tolerance. The encore needs some headspace. It can't bind at all on the close. Tc cuts the frame on 0 to .012 frame barrel tolerance. So if your barrel chamber is on the tight side and your frame is too, you can have headspace issues. They bind on the close. On a straight walled case you can't adjust by sizing short as you could with a necked case.