I actually extended the bolt on mine just before I sold it. I added a collar, which pushed it back the right amount. So, it is doable. As for the receiver, if you use metal plates and some good quality car body filler, anything is possible! 
When I want your opinion - I'll tell you what it is!
Sorry, I didn't take any pictures. I never actually modified my receiver, because I couldn't be arsed to be honest. There's a multitude of fillers out there, I'd go for an easy sanding one if I were you.
When I want your opinion - I'll tell you what it is!
For my MP001 I made a new bolt handle (gtound it out of steel) and attached it to the existing bold handle's "collar". It's still a work in progress, but I'll take a pic and it will give you the idea of what I've done.
Cheers
Ranj
I'm not sure how different the Bar 10 is to the MP001, but this is what I did.
It looks a bit rough at the moment, but it works. the new bolt handle / collar are one peice of steel (took a lot of filing 
). I included a lug (for want of a more technical word) so it would all slot together and turn the collar from the original MP001 bolt handle and joined them with epoxy resin to reduce the amount of wobbly free play. It works, the cocking peice needs shaping and the whole thing needs smoothing down and painting/bluing.
First pic is assembled.
2nd pic is of the components.
