Additional information, March 2015....

Recently one of our GTA members, Ribbonstone, noticed a slight bulging of the end of the tube on his QB79, in the thin area adjacent to the screw holes for securing the tank block.... The gun was operated for a time at 1250 psi.... In response, I have done an analysis of the tank block attachment, which is detailed in this thread....

http://www.gatewaytoairguns.org/GTA/...p?topic=105712.

If you are building a QB79 HPA conversion of any kind, you should read that thread.... If you are using more pressure than the 1100 psi factory setting for a Ninja SHP regulator, I am now recommending that you pin the tank block with two additional 4mm or 8-32 screws, or a 5/32" shear pin, between the O-rings.... If you want to be more conservative, you might want to pin the block when using the SHP regulator.... or even with a standard 850 psi Paintball regulator.... Complete information is in that thread....

Bob