Bulmer does a strip BSA 240 Magnum

[Benelli B76]

The ones that are occasionally affected by inaccuracy are very slightly deflected so 1 mm will make sure there is a total improvement.

Baz

[Shed tuner]

The ones that are occasionally affected by inaccuracy are very slightly deflected so 1 mm will make sure there is a total improvement.

Baz

Did this to mine years ago - unsurprisingly the problem is with .22s There is a crosspin in the plastic, so you can't go too large - as Baz says, opening out by a mill is just fine. Also, the pellet doesn't have to physically hit, just be too close, and it will still bugger up accuracy.