QB78 valve....again...HELP?!

[stevemag]

i had to replace the valve on my qb78...first let me say, i was patting myself on the back for remembering how to put that puppy back together.
i'm on vacation so i've been switching back and forth between the 78 and my x20 that MM just tuned for me, so i didn't notice the shot count  on the 78.
today i figured out that the 12gram cartridge was not fully being pierce on the valve end. i assume i did something wrong putting in the new valve.
aside from that it works fine, no leaks that i can tell.
can anyone tell me what i could have done wrong?

[rsterne]

The piercing on the valve end occurs on firing....

Bob

[stevemag]

The piercing on the valve end occurs on firing....

Bob

yes i know that, its not piercing all the way, just a nick to let out the tinyest bit of gas.

[warwolfmk2]

I have that happen now and then. As the piercing points on mine are sharp I traced mine back too cartridge's that are just a little to short so I now measure them and the short ones I set aside for my 2240. Doesn't have to be off by much to get a lite strike with the QB78. If I get two short ones the top and bottom cartridge usually wont pierce on mine.  Just remembered sorry minds going today if you use a small diameter washer between the two cartridge's you can compensate for the short cart's.                                             

[stevemag]

well i took it all apart and put it back together again and now it seems fine...

[stevemag]

 warwolfmk2 , pretty sure you are right about the short cartridges, problems seemed to go away but now its back. this time it was the top cartridge though.
low and behold it looks about 2mm shorter than the other. guess i better get a micrometer and measure the rest of them. thanks for the tip.

[TimmyMac1]

Take the screw out of your cap and drop a ball brearing in the screw hole. Add a washer equal in thickness to the ball diameter aND YOU HAVE MOVED YOUR PIN INBOARD ENOUGH TO PIERCE ALL CARTRIDGES ADEQUATELY. tHE TUBES WERE JUST FRACTIONALLY TOO LONG ON SOME GUNS AND THE WASHER BETWEEN THE PIERCING BLOCK AND THE TUBE CAP WILL CURE WHAT AILS THE GUN. "dang" capo lock. Sorry for shouting!

[stevemag]

thanks for the tip !!