O.K. I decided to have a go with polymorph. I bought a 250g tub off of amazon. It arrived without instructions but having read about it and watched some you-tube videos, I gave it a go. I put some in a jug (about half of it) and added hot water. The granules stuck together but didn't combine (I am not sure what the melting point of this batch is). So I poured boiling water on it. Gradually the granules went transparent and formed one lump. I took it out using a stick (wife over protective of cutlery) and thick black gloves. I formed it around the grip. It adhered to the stippling very well, in fact when I peeled it off, to reform it, particles of wood came off with it. It does not however adhere to smooth wood. I reheated it, having a better idea of the quantity and shape needed. I dispensed with the black gloves finding that despite the heat it was handle-able and reapplied it. I found I could make minor adjustments by heating the necessary area with a hair drier and/ or applying small melted amounts as necessary. It is easy enough to cut whilst warm (clear) but once it has cooled down and become white it is difficult.

The grip now fits me very well. It looks horrible (this stuff can apparently be coloured) and I don't like the feel but take solace in the fact I can take it off relatively easily. I am unsure if the grip size is within spec now and the gun needs convincing to go back in to its steyr box. I hope it improves my scores but only time will tell. I have taken some pics but my son has run off with the camera download cable. Thanks for all the responses.