I currently have 5 MarkI's , a MarkII and 2 MarkIII's. One MarkI is the SR model, but I don't shoot it. I just can't pick between them all as far as accuracy. All are reduced stroke and home "tuned". My version of tuned is a Maccari(ARH) kit or spring that happens to fit a factory guide nice and snug. I'm also a big fan of the Maccari Apex seal, if it's the older style that is a bit more pliable. My guns are mostly old beaters that my FT friends left behind when they went pcp. Accuracy is still spot on with all of them.