Advertised widely in the airgun mags of yore as "The Ratter"...(in more ways than intended)
I had one - Nastily finished in a cross between red-oxide and yarnish , sharp edges all over the little bugger and slathered in nasty smelling brown grease everywhere, came complete with a comedy trigger and tool marks all over the shop.
Archer Airguns used to do a reworked version that looked a whole lot better and I adopted a similar style on my own. Can't see any pictures on the web - but one of the airgun mags has Stephen Archer writing for them now - so he'd be worth talking to...
People are still mucking around with them and here is a Dragunov styled one...http://topguns.ru/zhdu-mnenij-bam-xs-b3-1/?n=10
Its still a nasty little turd underneath though...