I just received a new 2240 from AirGunEric with the intention of converting it to .177 cal.... I already had a 10" barrel from a 1377 and a Crosman steel breech, so the major parts were looked after.... With our wonderful rules in Canada, it is critical to keep the gun under 500 fps as I have no intention of ending up with a Restricted Firearm that I can only use at an approved pistol range.... I have previously built a 1750 with an 18" barrel and carbine stock that shoots just under 500, so I already have some ideas to try.... Recently, however, I got a tiny 0.070" ID transfer port from Eric, so I thought that would be my first trial.... Eventually I hope to get the gun tuned so that the valve is pretty much self-regulating so that the velocity is more or less independant of temperature and the velocity right in the 490's....

I disassembled the 2240, deburred the tube, polished up the trigger and replace the spring with a lighter one and fitted a piece of brass tubing for a spring guide.... I put the gun back together with the .177 barrel and breech, loaded up a CO2 cartridge, and fired a couple of shots, confirming that the velocity was too high.... I tried some smaller transfer ports, and even one that was only 3/32" ID (0.094") wasn't restricted enough.... The 0.070" port worked just fine, however, producing velocities in the 460ish fps range at 70*F.... I loaded a fresh cartridge and shot a full string, firing one shot every 30 seconds.... By the time I had fired about 20 shots the velocity settled in at about 430 fps due to the cooling effect of shooting, and then it plateaued, falling to about 420 fps by shot 60 and then taking a dive over the next 15 shots.... Anyway, at least I have a baseline for further work....

Bob