Has your bsa r10 got to be .177 there is a .22 r10 mrk1 on gun trader £350 from a gun shop http://www.emmettandstone.co.uk i bought a r10 mark1 .177 with the mark 2 upgrade on free adds for £375. just lucky i guess. did you know the rotex is based on the umarex 850 airmagnum same internals you just can't take of the bottle i did a conversion on a airmagnum 850 .22 it was sweet i am selling all the bits on here to do a .177 you can buy a wood stock for the 850 airmagnum from Guntuning