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Crosman 1760 Single Pump

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cfellows:
I've started a project to convert my Crosman 1760, which was originally a 2260, into a single pump.  I was originally going to use the 2260 valve tube, but found a piece of 7/8" seamless, stainless tubing in my stock pile and decided to make it from scratch.  Here are some pictures of my meager beginning.







I'm going to use the original 2260 valve that has had the original tip replaced with a Bryan and Associates Bulk Fill tip.  Here is a drawing:



If there's any interest in this project, I'll continue to post pictures of my progress.

Chuck

lunatech:
I for one am quite interested to see more of this.

rsterne:
You will likely find that the 22XX valve is too large an internal volume for a SSP.... You need a small valve volume to build a very high pressure in that single pump.... I would try stuffing the valve with a tubular spacer to reduce the volume if/when you are unsatisfied with your initial tests....

Bob

cfellows:

--- Quote from: rsterne on March 10, 2013, 02:27:12 PM ---You will likely find that the 22XX valve is too large an internal volume for a SSP.... You need a small valve volume to build a very high pressure in that single pump.... I would try stuffing the valve with a tubular spacer to reduce the volume if/when you are unsatisfied with your initial tests....

Bob

--- End quote ---

Thanks Bob.  I have read over a lot of your posts in several forums and see that you have contributed a lot of information.  I appreciate your input.

I hadn't measured the valve's internal volume and figured I'd have to make some adjustments once I got the gun assembled and tried it out.  I mostly do target shooting at less than 20 yards so am not interested in a lot of power.  However, I am interested in consistency and a fairly flat trajectory over that distance, so I expect I'll want 500 FPS or more with a .177 caliber.  I'm guessing I'll need around 1000 PSI to get that, although I'm also guessing that the volume of stored air plays a role in the muzzle velocity... just don't know much.

I'm grateful for any and all advice...

Chuck

cfellows:
Got the linkage which connects the pump handle to the piston finished today. 





It's made from 3/16" thick, cold rolled steel, 5/8" wide and about 5 1/8" long.  The distance between holes is 4.5".   The pump arm is made from 3/8" thick aluminum with a 3/16" slot milled in it to accept the linkage arm.  The forearm will attach to the pump arm and be quite a bit longer, extending almost all the way to the trigger guard.   Most of the aluminum pump arm will be hidden inside the forearm.

As I get older, I find my technical vocabulary is shrinking, so I hope you'll overlook the occasional use of the wrong term!  :(

Next I'll start on the piston.

Chuck

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