the only difference that i've noticed is that the breech area of the mk1 is made of machined round steel bar, the mk2 looks to have machined alumimium square stock, i think everything else is the same...
here's a pic of the breech of mine though i don't have a pic of a mark2
john
oh, i don't think it's greedy to have two, there's one or two on here that has squillions of bsa airsporters- that's greedy