Crosman 760 roll pin repair

[Quick Cal]

I'm working on my pre 75 760. Well it's a bit of a Franken-gun I think. The receiver is later I think since it has a serial number. How ever, it has the early pump and compression chamber. So I'm calling it a pre 75 since the tube cap is from 73.

So the roll pin hole is all wallowed out. It had a 3/16'' screw in it when I got it. It was bent, and loose. It was rocking all over the place and really elongated the hole for the roll pin. I put a 3/16'' roll pin in there when I had everything apart cleaning the gun. Suddenly the forearm would not close all the way. And I was not getting any air pressure. Never was before. I thought I assembled something wrong. I must have tore it apart 50 times.

Turns out it was that bigger roll pin, for what ever reason, was not allow the linkage to function properly. I actually think it must have been crooked in the elongated holes. I tried a smaller nut and bolt that I had and it works now. But it's way too sloppy loose.

So I've ordered and upgraded roll pin that has a screw going in from each side. But I fear the hole might be too big. What have you guys done to repair something like this? Thanks for any info.

This pic does not show how bad it really is,,,lol.

 

[Treefrog]

Dang... That's what I was afraid of when I saw the bolt and wing-nut that it came with.

You're not out of luck. I can see a number of options. Welding the holes in the tube closed and then re-drilling them the correct size and doing the same with the pump-arm. (The pivot is zinc, so there's not much you can do with it.) Replacing the pump-tube along with the wallowed out pump-arm and pivot. Or drilling them all out on center and then using a larger roll-pin (or putting an insert through the the arm, pivot and tube).

There are spare parts out there, so you're not out of luck. Alchemy AirWerks - Home might have what you need. They should have the necessary seals, too.

You might want post about it over at the Gateway To Airguns Vintage Airgun gate. There are a lot of knowledgable people over there.

Luck,

J~

 

[Quick Cal]

Did you call me a wing nut,,,,lol.


What I'm mostly worried about is getting the hole exactly centered. What ever method I use, I think the hole needs to be right on the money or it will throw off the depth of the pump cup? Am I thinking right...lol?

Since I have the threaded screw that holds the pump cup can I assume this is adjustable? Then if my hole was off I could just adjust the cup length? Is there a write up or video on how to do this?

 

[Treefrog]

Lol. Nah, that was the previous owner.

Centering everything would be important. I don't know just how important. The pump-cup depth is adjustable, so you're good to go with that. The pump-arm hole was factory hardened, so it would need grease to reduce wear since the hardening has been worn through. You can probably find the parts/knowledge you need over on GTA. There are parts out there if you want to replace some of it.

And don't worry about it being a frankengun. Mine is one of my favorites. It has the rare (vaunted) rifled barrel.

J~