Valve shim used to reduce gas venting with WE rifle and other models of GBB magazines.
Allows a GBB-P to run down to 32 degrees with pure propane and 25 degrees with MAPP Gas (in conjunction with Ice Pick valve). This shim strictly aids in efficiency. Compatible with WE rifles and TM/WE/KJW pistols. Once installed properly, it will run the magazine dry without venting.
Tested here with TM Pistol with sub-60 degree magazine.
Tested here with Stark Arms GBB: