I read you need a serial number to know the year and I can't find one anywhere. And it says patent pending. The stock is plastic that looks like wood. Any advice? 
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Tuning I'm new here. Trying to repair old Powermaster 760.
- Thread starter Jimdogs
- Start date
I found this on the internet. However do not ask me on resealing and airgun repair, I am all thumbs. I bought a seal kit and new valve assembly for about $80. Installed it all in my Crossman 761XL and it still leaked. It is being repaired at Phil' Vintage Airgun Repair with 2 other pumpers. Sticking to lawn and gardening.
Model 760 Powermaster
Model 760B Pneumatic, BB repeater, .177 cal. single shot pellet. (Model 760 w/ black stock & forearm) rifled barrel 1988-present
Model 760 Powermaster
- First variant. Wood stock and grooved wood forearm, brass bolt, smooth bore 1966-1970
- Second variant with styrene stock & forearm & scope mount groove, brass bolt. Checkering on forearm 1971-1974
- Third variant, self-cocking w/styrene stock & smooth wood forearm. 1974-1975
- Fourth variant w/ABS stock & forearm. 1975-1977
- Fifth variant w/manual cocking. Brass handle for bolt smooth bore 1977-1980
- Sixth variant w/plastic bolt. metal receiver, rifled barrel 1980-1983
- Seventh variant w/plastic receivers & w/welded sights. 1983-1991
Model 760B Pneumatic, BB repeater, .177 cal. single shot pellet. (Model 760 w/ black stock & forearm) rifled barrel 1988-present
- Eighth variant w/shortened barrel w/pressed on sights. Rifled barrel 1991-present
- Ninth variant w/fiber optic front sight and 5 shot manual clip. smooth bore 1991-present
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Hey Jim,
If you look at the front of the pump pivot beneath the barrel, you'll probably find a couple of numbers like this.
They'll tell you the month and year that your rifle was manufactured. This one was made in April of '72. If yours has the heavy plastic (polystyrene) stock and forearm, it's of the same (early seventies) era like this one.
They're not too hard to repair. Parts are available from a few places. Mac-1 Airguns, among others. Here's a parts breakdown -
Luck,
J~
If you look at the front of the pump pivot beneath the barrel, you'll probably find a couple of numbers like this.
They'll tell you the month and year that your rifle was manufactured. This one was made in April of '72. If yours has the heavy plastic (polystyrene) stock and forearm, it's of the same (early seventies) era like this one.
They're not too hard to repair. Parts are available from a few places. Mac-1 Airguns, among others. Here's a parts breakdown -
Luck,
J~
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Thanks, All mine shows is 4. Please see picture. Am I missing something? Of course why would I have normal one from my teen years. 
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When I zoom in, it looks to be double stamped so maybe 44? Like they didn't move the die over far enough before the second strike.
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^ I think he's right. That does look like a double stamp. If so, then April of '74, probably. Those stamps are known not to be done very consistently. Perhaps the Crosman pivot-stamper-guy was low on the totem pole and it's reflected in his less than firm or accurate work. I have a pivot like that from an early gun that isn't stamped at all.
Post some more pics, Jim. I'd like to see the rest of the gun.
The exact year/month of manufacture won't affect the parts needed to get it going. You're close enough to get the right ones the first time.
J~
Post some more pics, Jim. I'd like to see the rest of the gun.
The exact year/month of manufacture won't affect the parts needed to get it going. You're close enough to get the right ones the first time.
J~
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I wasn't sure if t was a double or it looked like at first glance that marks were the edges of the tamp
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Thanks, Jim. Looks like it's all there and you've got a fun project. The gold trigger is a bonus as it reinforces the era of the build.
Mind the BB-retention button on the back of receiver when you pull the sides apart as it can launch the spring across the room.
The internals will look like this.
And the valve will look something like this. Probably less crusty... (I only bought this one because it had never been disassembled and was $10.)
Good luck and do please keep us posted. They're fun little guns when they run!
J~
Mind the BB-retention button on the back of receiver when you pull the sides apart as it can launch the spring across the room.
The internals will look like this.
And the valve will look something like this. Probably less crusty... (I only bought this one because it had never been disassembled and was $10.)
Good luck and do please keep us posted. They're fun little guns when they run!
J~
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Thanks for your help. I will be starting on it and will keep you up to date. It does look like fun.
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I tore apart a 1980 760 about a month ago to clean and reseal. It went okay but I did need to research along the way. Besides the usual tools you'll need a sturdy dowel and mallet to knock the brass air chamber out of the tube and a propane torch (or similar) to heat the air chamber to soften the Blue Loctite. Be ready to pad the teeth of two pairs of channel lock pliers to get the warm chamber apart. The pads are so you don't scratch the brass.
When you put the air chamber back in the tube, use the dowel to move the outlet port into the correct position. Keep pushing the new gasket in with your thumb as you switch poking the dowel in both ends to adjust the chamber. You'll feel it when the little gasket pops into place. It's a fine tune.
A basic tune kit for my model was the outlet gasket, two gaskets for the air chamber, a valve, and a pump cup. There was also a plastic barrel-shaped part (like beer barrel, not rifle) for in the air chamber, it goes between the spring and the valve. My model had a much smaller plastic part that mated to a similarly-shaped aluminum piece. I reused those two parts.
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I don't know how much this service manual applies to your model but it helped me.
Model 760 (Drop Hammer) Service Manual
Model 760 (Drop Hammer) Service Manual
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Am I missing a piece? I bought a seal kit and it came with a 4th seal that was supposed to go in another cap that goes to the left of my pic? But it looks like the one in the discussion above. I don’t think I have part 140A056?
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The part that you reference goes inside the pump-tube. It surrounds the end of the valve and guides the air into the barrel through the transfer port. Look inside the pump-tube and you'll probably see that it's still there. Sometimes they stick. That's all I got...
Cheers,
J~
Cheers,
J~
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Hmmm, I found another article online that talked about how to pull that 4th seal out from inside the brass cap I do have. I did that and was able to get like 525fps, so I’m thinking I don’t need the piece I thought was missing. This gun is stamped 124, so Dec ‘74?
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Those numbers sound reasonable. It's shooting a tad harder than any of mine do.
I think you're done. Shoot it and enjoy!
J~
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