Hi All, I have a freinds BT-4 that will not get over 270fps he just switched to hpa and put a heavy velocity spring in. the gun was just cleaned and lubed what are we missing my old 98 custom would go over 300 easy with a velocity spring kit
How old is the gun? I've heard that on the older BTs, if you're firing at a high rate, the ASA port isn't big enough and you get "drop off." Just a thought. Mine is less than a year old, upgraded porting, rip clip, egrip, and it works perfectly!
Looks like I have doubled up my post My freind has the stock installed so I dont think an rva will work we did put a heavy velocity spring in and shimmed it so it does not slide back into the stock internals are polished up and he replaced the power tube what are we missing?
try backing out the asa a bit. maybe its blocking it some. I got my bt4 used on ebay a few months ago. Ive got a ninja HPA tank as well. I couldnt get it to shoot over 250.
I polished the internals, added the red spring from the BT spring kits. I also put in a JCS blue power tube (one for the Salvo/98 markers) and a superfly bolt. ALso, when I put the valve back in the power tube, I put electrical tape on the raised ridges of the valve. cutting a hole through the tape for the air hose hole and the holes where the body screws go into. this helps seal it so air doesnt escape through those areas. Now it shoots real hard.