I got my Baikal spare parts from a chap on eBay from Russia from a seller called super-custom. Good seller. I would recommend asking him to courier it though if you want it in faster than 3 to 4 months with our brilliant postal service.
have a look here ! If he doesnít show the item on eBay give him a shout, he might be able to source it, he is very pleasant. I upgraded my mp-61 to a gas ram and itís brilliant .