Let me start off by saying that you managed to get about twice as many shots from your mod.48 as I did with mine. I had springs fail at 2500,2000,and 1500 with a truck ride each way before I figured it was cheaper to buy the parts and do it myself. Faster to, an hour so compaired to two weeks minium. I have tried the kit J.M. provided a few years ago,with dissapointing results for me,lost over 100 fps and that didn't cut it. The gun shot smoother,and was very easy too cock but this was not what I was wanting with this rifle. I am now using a Vortek kit in mine with very good results so far. Mine is .177 cal and is averaging about 830 fps with Crosman premier heavys 10.5 gr. Only have about 500 rounds thru it so far, time will tell the tail.Gary
It has been a while but I seem to remember is was lower than that, more like 680 or so. Now I am not knocking J.M. parts, just wasn't for me with that rifle. I have used his springs and seals with very good results in a couple of 34"s.Gary
Never use the factory ratings. Maybe 900's. Those results were atypical of a JM kit.