Anybody put a .25 barrel on a disco ?

[lloyd-ss]

I am curious if anybody has put a .25 barrel on a disco ? 
Can the valve supply enough air for .25 by just changing the hammer spring?  I'd think that other mods would be needed to get it to make real power.
Thanks,
Lloyd

[Dead nuts dog]

check airgunsmiths, I have heard of a .32
let me know tho, I would love to do the same

[JonnyReb]

 I have SO been wondering the same thing.. with a power valve it would seem feasible and i think Bob put a 9mm on his. Or how about an air shot gun based off the disco? Sorry Lloyd i ran with it.. i'd love to have some mods to give me a reason go go bigbore with a disco. I think your just the maan to find out considering that everything you need is just feet away from you..

[lloyd-ss]

Jeff,  I bet Bob will weigh in on this shortly. 
The transfer port seems a little restrictive, too. And the volume inside the valve body is kinda puny for a .25 cal.

[Dead nuts dog]

right give it up! I would love it

[rsterne]

Yup, been there, done that.... with a bored out valve and ports and a heavy hammer spring I got to 58 FPE with 31 gr. Kodiaks for just 9 shots between 2500-1700 psi (~100 psi drop per shot).... I backed it down to 45 FPE and now get 11 shots starting at 870, peaking at 906, and back down to 867.... That was with JSB 25.4 gr. Exact King pellets.... filling to 2100 psi and shooting down to 1300.... Efficiency is 0.96 FPE/ci over the 11 shot string....

Part of the trick to get the big numbers with a Disco is to bore out the gauge block to flow more air and also flow the valve inlet.... If you don't, the air can escape from the valve easier than it can get in from the reservoir.... I used a 5/16" mill offset to the centerline to bore the gauge block (you can't just drill it on the centerline or you will destroy the seat for the gauge O-ring).... On the valve inlet, I used a tapered reamer, then a 7* tapered mill on the inlet and then used a countersink to smooth the flow on the front of that and on both sides of the gauge block....

The valve was bored to 0.60" ID and the threads on the valve front end shortened to 0.30" long to increase the valve volume.... I slimmed the valve stem to 0.115" and ported the valve exhaust port using a 5/32" mill on a 20* angle and then smoothed it out with a Dremel.... The diameter at the valve seat was increased one drill size (I think it ended up at 15/64" but can't find my notes on that).... Transfer port was a poly port with a 0.166" ID and the barrel port was 11/64".... I never tried my .25 with a stock valve as I had already modded the .22 version to 52 FPE before I went to the .25 barrel....

You mentioned 9mm?.... I recently did a 9mm Carbine with a ported Disco valve (ID not bored out) and got a peak of 63 FPE with only a 16" barrel and a 2000 psi fill.... That was 606 fps with 77.8 gr. EunJins.... I have a 24" barrel coming (and also a .308 x 24") and will report when assembled and tested.... I'm guessing 70 FPE is within reach, maybe more.... 

A stock Disco with just a barrel swap to .25 cal ?.... I'm guessing over 30 FPE with just adjusting the proload on the stock spring.... significantly more than that (40ish) with a heavier hammer spring and a 2400 psi fill.... I got 34 FPE with such a setup in .22 cal for 15-18 shots with heavy pellets (Kodiaks, EunJins).... just a spring change and a higher fill pressure....

Bob

[lloyd-ss]

OK Bob !  This should be called , "Pimp my Disco."   I like it.  You have left nothing untouched. You even skinnied the valve stem.
Seriously, a very thorough upgrade.  Have you ever tried actually making the valve with the integral seal?  It looks like it ought to be fairly doable after a couple of failed attempts.   Then you could really dump the air into the xfer port.  I understand what you mean about opening up all the inlet choke points.
Nice info!
Thanks, Lloyd

[rsterne]

I actually really like the overmolded Disco valve stem.... I mistakenly tried to slim one down and found out that the metal inside is nearly as big as the OD of the plastic part.... as half the plastic departed the stem.... 

I'm not sure what you mean by "making the valve with the integral seal".... 

Bob

[lloyd-ss]

Bob, ok, interesting.  I have a very early Disco  and the valve is not overmolded.  When I saw the term "overmolded" in the parts list is didn't seem right and now I know why.  My valve was machined with a groove in the mating face of the valve into which an o-ring is inserted and then the edge of the valve is "rolled" around the entire perimeter to capture the o-ring onto the valve. Only a tiny portion of the o-ring is left exposed, just enough to make the seal against the valve seat.

[rsterne]

Interesting.... You must have a pre-production prototype, or nearly so.... I've never seen one like that.... The ones in all the valves I have look similar to the one in a 1377/2289 pumper (white plastic on a metal stem) except larger diameter.... They have a 1-piece metal stem with a 3/8" diameter head, just like an automotive poppet valve.... Then the plastic is "overmolded", completely covering both sides and the OD.... although it is VERY thin on the outside edge....

The valve in an RWS 850 uses an all metal poppet valve seating on an O-ring in a groove in the valve body from what I can remember.... The valve has a stem sticking out in both directions and the "front" end rides in a three-legged guide to keep it centered.... Weird arrangement but it seems to work OK....

Bob

[MountainMan126]

Check the Mountain Air website, I believe they do it with an added fee .25 l/w barrels on a disco. I think they are just selling the complete rifle, don't know if they do upgrades.

Ethan

[lloyd-ss]

Check the Mountain Air website, I believe they do it with an added fee .25 l/w barrels on a disco. I think they are just selling the complete rifle, don't know if they do upgrades.

Ethan

Ethan,
Son of  a gun if they don't.  And the prices look pretty reasonable.
Thanks,
Lloyd

[rsterne]

I got my barrel and bolt from Mountain Air.... it comes with a piece of Poly Tubing as well....

Bob