760 Pumpmaster Blowing In My Face

[ezman604]

As the title states, my 1967 Revelation 760 Pumpmaster gives me a puff of air in my face when fired. I don't THINK these have an O-ring in the breech. Not at home to check at the moment. Just thought I'd post to see if anyone has experience with this issue and how you fixed it. Only thing I can think of is replacing the barrel or the probe. Problem is I want to keep it as original as possible, since it's the very first model. It still shoots hard but...
I may have to just hang onto it as is as a piece of history.
SAFE & Happy Shooting!!!!
Dave
 

[mav72]

Wasnt sure of the differences of that design version so I had to look it up...

http://www.crosman.com/pdf/manuals/C760SC-EVP%20&%20PL.pdf

On that particular version people cut a groove on the bolt and add an "O" ring... Or if you have the tools and the know how and don't want to mess up your original bolt, I've seen people make thier own bolts with an added "O" ring...

EDIT: I've also seen people add a brass sleave to stop the air but I don't know how well it works or lasts...

[ezman604]

Thanks,
Hmmm....got the old gears a turnin'.

[Just_T]

Thanks,
Hmmm....got the old gears a turnin'.
 

I'll be watching this one closely, Dave...the Tootsie Roll I picked up blows air out of the bb reservoir too... 

[ezman604]

Will take a close look at it soon. I may either try to fabricate a probe or try to find an old new stock somewhere. Might even buy a parts gun. I'm wrapped up this weekend and just got in a new .25 Condor SS I'm trying to get time to set up and get acquainted with. Just too much fun and not enough time.

But, I'll report back with my attempts at a remedy.
Thanks for the responses!!!

[mav72]

When you get er done curious to know how it turns out too... I've been trying to stay away... When my gears start turning, it means more money is going to be spent...  This stuff is real fun but not for my wallet...

[ezman604]

Was about to order a replacement bolt from JG Airguns and went ahead and dropped John a message describing the issue. He replied almost immediately that this is a common problem with the 760 Pumpmaster. He said I COULD make a new oversized probe (bolt) and lap it down to for a tighter fit. He's not sure if my idea of cutting a groove in the end and adding an O-ring would work. It would seal for sure but might cause me to cut off and lose the magnet on the end.
Again, I'll take a closer look this weekend hopefully. IF I can chuck the bolt into my lathe, I think cutting a groove and adding an O-ring is the best bet.