Pellet gun question

[bortle]

So I shoot a lot of air rifles in the basement and back yard. Cheap quiet fun. Experimenting with different pellets. 7.9gn shooting dead on . one ragged hole dead center. Switch to 11.57gn and shoot one ragged 1" to the right. No change in up and down just all to the right. Can anyone explain this? What are the actual physics of this? If it matters I'm using a RWS 54 Air King with a scope off a bench at 30ft.

[Delkal]

Pretty sure it has to do with barrel harmonics. When you shoot a rifle the barrel starts whipping around and if the bullet leaves the barrel at the wrong time it can shoot to one side or up and down. This is why reloaders can find a more accurate load by varying the charge by just a few tenths of a grain.

An air rifle is less powerful so the barrel should not flex but the locking mechanism is not as strong so it might give a little wiggle. Or it might be the position of the piston. Go for the pellet that shoots the tightest group and adjust your sites for it.

This is just my guess.

[bortle]

Both shoot pretty tight, but the heavier ones cost more.