I believe I am aware of most differences. I am having trouble finding power specs of the original version? I see in .30 (what I’m mainly interested in) that the mk2 is rated up to 91 ft/lbs when i look up the vp model with 600 mm barrel. I have no idea if this is an across the board maximum rating with a 700mm barrel or specific to the 600? I guess what I’m asking is in .30 cal with 600mm barrel what would the approximate max energy to be expected out of the mk1 ? What about mk2? Trying to figure out if the mk1 would be a worthy gun to buy.