After seeing Minte posting about Crosmans tune ups he does for what I think is a very reasonable price I had to take him up to do a tune on my 2250b.
He started with doing a test of 48 shots to see how it performed through the Chronograph. I have attached a graph of 47 shots (not including the first one to get the valve filled with CO2). I quite surprised by it getting close the 550 fps that Crosman quote with 519 fps and being pretty consistent for the first 30 odd shots, with it sitting over 8 Ft-Lbs for most of those. Minite did state that he used Accupell which are quite light at 14.6gr.
From there the 2250 has been dismantled, the valve disassembled and the gas port ground out to remove the elbow to allow a smoother transition of gas. The valve cap has had a few threads removed to allow more gas into the valve.
A little photo run down on, thanks Mintie for the photos.
The Crosman 2250b dissembled
The dissembled valve
The end cap having some tread removed to increase the volume of CO2 in the valve.
The powerlet pin having some work done.
The valve before having the elbow removed
The valve after having the elbow removed
Mintie had put it all back together but was not happy with the results of 9.8 FPE up from 8.6 FPE, this is about 550 fps at the muzzle. The shot count dropped down to 20. He is having a think about it and I am sure he will find the problem.
Issues and final result
When I had installed the steel breach the rear bolt had pushed into the hammer spring. This was causing the gun to lose gas because of it bouncing.
A few more tweaks and the rifle came out to give mid 10’s FPE and a shot count of around 25. He also got it up to 12 FPE but only 12 erratic shots.
At 10 FPE it will be good to take a rabbit at 30m and hopefully will be able to test that out shortly.
Next on the list is to bulk fill and use paintball marker tanks.