Experiment with different front rests,i have tried a variety of different makes and types.
The PCP is not a problem of course!but the springers?
I have got the best results from my Terrus and Gamo 440 using an MTL plastic adjustable front rest,neither springer liked the moulded rubber top,although this is not hard the fact appears to be that it imparts just a minimal amount of grip to the stock and while both rifles are almost free of any recoil movement it was sufficient to cause innaccuracy,so off came the plastic and rubber top and i fitted a piece of ply about 5"x 1.5"x 1/2" thick covered this with a peice of cork tile and on top of this a piece of carpet tile, so not soft but gives the stock a surface that it can move on,i know that this is contrary to everything that i was told, but resting the stock around 3" back from the front and supporting the underside of the butt with my non shooting hand and the lightest possible touch with the trigger hand has given excellent results, providing i remember to concentrate on my eye alignment and the keeping the crosshair on the target and not worrying about seeing the target clearly.
Don.