I have just bought a used impact mk2 and I’m having some issues it’s grouping very inconsistently every few shots I’m getting pellets move up to an inch off the poi

I thought it could be the mag as the centre disk is a little lose but I tried some one else’s and that was similar. It also seems to shoot in a string so pellets going in a line If that makes sense

I used and tried every pellet I could find yesterday and nothing helped the issue, could constantly swapping pellets be a problem?

What about cleaning the barrel should I try this ? Iv seen a lot say never clean an stx impact barrel that isn’t brand new


Currently I have a 1200.0 cricket bar