2260 disco conversion

[captwoody]

I converted my 2260 to pcp with a disco tube and valve, but she only shoots 670 on the chrono i thought i would get closer to 800 in the 22. is my hammer spring to weak. i used the parts list that is stickied on the crosman forum and i think the adjuster and spring are from a 2250.I already did the mac1 upgade on the barrel and seal. should i drill out the delrin seal a little more since tim set it up for co2
thanks for the help-woody

[rsterne]

The hammer spring in a Disco is stiffer than the one in a 1377/2289.... which is stiffer than the one in a 22XX series.... Here is a graph of some testing I did with the three different hammer springs in a 14" and 24" barrel.... The valve was a dead stock 22XX (it even had the piercing pin in place), and fed directly with HPA....



You can see where the velocity peaks with each spring and the pressure at that peak.... The solid lines are a 24" barrel and the dotted lines a 14" barrel.... I was not using an RVA, but just the stock rear spring seat (tube plug).... If you use an RVA you can increase the velocity somewhat.... but you should still pick the spring for the velocity range you want.... For 800 fps, you need a Disco spring....

Bob

[threex4]

When I did my 2260 I used the disco spring and cut my barrel down to 14-1/2" . with out the useing any power adjuster  I was avg around 750fps for 20 shots.

[captwoody]

Thanks will order springs

[The Knot]

3x4 thats very nice looking gun stock is sweet love the disco

[threex4]

Thanks , that stock was a James Linthicum DIY before he went MIA.  This was the same design he used for his Disco stocks , minus the gauge hole, no gauge on my 2260 PCP.
The cap on the grip and stock I didnt like so I didnt put them on, but it still has a good look with out them.