When I bought my first Walther the previous owner had used high strength velcro to put a 2" deep laminate block on to the base of stock. I have seen it in B&Q etc cheap and was very effective as he could move it fore and aft etc as required. Peels off easily when you find a better solution with a hair drier. He put the soft furry bit on the stock and the hook bit on the block.
Without the block the furry stuff acted like non slip tape as well.
Cheap but effective!
FTP900 +Sightron S111 10-50 x 55
AA Pro Target in FWB FP70 stock + MTC Mamba lite
Daystate Airwolf + Bushnell Elite 6500
" life is about the memories we hold and not the things that we own"