Project seven - six - zero

[Toolmaker]

I've decided to try and hot rod a Crosman 760. Yep, that's right, Crosman's bottom line el'cheepo plastic gun. Why, you ask? I dunno, why not? I don't think it's any different than modding a Cummins Tool B3 and I don't particularly like B3's. As a matter of fact, I traded two B3's for one and a half 760's. My victim is a 1989 model that's in overall good shape but shoots a little weak. The plan is to increase power via the standard Crosman pumper mods, ie: flattop piston & valve etc, give the trigger a better feel, and increase the structural integrity of the plastic receiver. I may very well surpass what the plastic parts can handle. If it breaks I haven't lost much and 760's are cheap. The main thing is I'm havin' a blast!

 Below is a pic of the rifle and the flattop piston / valve that I made.

[1377x]

cant wait for the next update

[Toolmaker]

Installed the flattop piston today. Also installed hardened and polished trigger and sear pins. Polished the sear. Reassembled gun. WOW what a difference in power! Gun shoots much harder now. I haven't made any mods to the valve (yet) other than the flattop. I don't yet have a chrono so I compared it to my son's new 760 (he got it for Christmas). Mine will put a Daisy wadcutter through one side of a steel can with 10 pumps at 10 meters. The new 760 will only dent a steel can with 10 pumps at 10 meters. One problem I now have is the bolt will not stay closed. A lot of times it is being blown partially open. I will have to come up with a better closing & sealing bolt setup.

 Below is a pic of the hardened pins and the polished sear. The trigger only has a slightly better feel, got more work to do there as well.

[Rontier]

REPORT ON ANY MOD'S YOU PLAIN ON THE BARREL?
OR SEAL, MINE IS FROM THE 1980'S & A GOOD 10MM GUN, IT WILL ONLY DENT A CAN !!
BUT WAS WONDERING IF THEY MAKE A RIFLED BARREL FOR THE 760?

[Toolmaker]

My 1989 has a rifled barrel. I also have barrel from a '92 in my parts stash, it's rifled too.

[Rontier]

:) YOU LUCKY SHOOTER!!
MINE IS A SMOOTHY..
BUT SHOOTS BB'S OK, & PELLETS OK?
JUST A 10MM GUN ? PAST THAT IT'S A HIT OR MISS!
BUT STILL DOES OK FOR WHAT IT IS?

[jake]

this is going to be a cool biuld!

[ShadowShot]

I had a 760 as my first pumper years ago. My was it accurate with bb's and even better with pellets. I'm guessing this was back in the mid to late 70's. Man I wish I could find one like her again. Todays 760's are like the rest of the new models, cheap. Best of luck with that pumper. My old one would punch holes in the trash can with bb's. Tree rats, I was their worst nightmare till I blew out the seals. I guess, 20 pumps or more.

[Toolmaker]

Made some more mods to the 760. I started with the bolt. This 760 will not be shootin' BB no more so I decided to remove the magnet and extend the probe in the bolt. I also stuck a piece tubing between the bolt handle and body to give it a little more "spring" and  see if it would help keep the bolt closed. I'm real pleased with the probe but the bolt still don't stay closed if I pump it more than 5 times. Next, I turned my attention back to the trigger. I added a couple of set screws to the trigger, one for pull and one for over travel. There is a metal "ear" that keeps the bolt from being cocked if the trigger is not all the way forward. I had to cut the end of it off 'cause with the set screws limiting the trigger travel, it wouldn't cock. Now the trigger is still a little heavy for my taste but it is crisp with almost no creep. One drawback to the setscrew location is that they can't be adjusted with the trigger installed so it takes some fiddling to get it adjusted right. I actually like the feel of this 760 trigger better than my 397 Benji. I'm gonna pull my Benji back apart now and use what I've learned on this 760 trigger to see what I can do for it.

 Here are a few pics.

[normal]

Couple thoughts.

 Might be able to cut the notch inside the receiver deeper, or even clear through the side for more catch surface.  Your tube would help push the handle out a little further to engage better.  You'd want to push the handle in pretty hard when you cock to minimize wear on the corner that helps hold it shut.

Another one probably not in the spirit of what you're trying to do could be a catch piece mounted on the outside with a pivot behind the bolt handle slot.  Pivot up, say, to cock.  Let it drop in behind the handle to hold the thing shut when you fire.  EZ to make it take up the play in the original set up.  Looks like pivot could be a pin clear through the thing since you don't care about feeding BBs.

Fun stuff.  More pretty work!!

[Toolmaker]

Thanks for the ideas Norm!