Okay, I got some chrony work done on my Disco this morning and I'm getting 85 shots from 2000-750 psi. These 80 shots start at 642 fps, go up to 763 fps, and come back down to 670 fps. This is strictly a 30 yard gun for pest bird removal, so I chose 40 shots from 1500 psi down to 900 psi. This gives me a 40 fps spread (5.2%) which I figure is fine for pest removal. HOWEVER, if I were to install a regulator set at, let's say, 1000 psi (750 fps) could I fill the gun to 2k and possibly get 60 shots at a relatively stable velocity? Currently I'm getting 65 shots before dipping below 1000 psi, and I figure the regulator takes a few cc's of capacity, so I'm thinking I could possibly get 60 good shots? That would make this a great gun for an entire day removing sparrows/starlings at the permission.There was a member here selling custom regs for the Disco (and Mrod, I think) a few months back. If that is you, PLEASE PM me again. You PM'd me once about it, but I didn't want to go this route back then. Thank you.
Chris, regulated is the sweetness for small caliber rifles.Remember that revelation of accuracy you discovered when you switched from springers to PCP? Regulation is the next most significant step in my opinion.
Tuning a regulated rifle for good efficiency is pretty easy compared to a conventional PCP. The air pressure seen by the valve is always the same so there is no magic balancing act between high pressure/low lift versus low pressure/high lift and dwell to deal with. Generally if you can trim hammer strike with an RVA, you won't have any trouble getting it tuned for good efficiency.
Don't forget to allow some volume between the regulator and the valve or you will lose power compared to what you expect at the setpoint pressure you choose.... A plenum of 1 cc per FPE is recommended, and that assumes no restrictions on the inlet side of the valve.... You will have to reduce the preload from your current tune or you will end up with an air hog....Bob
Since you are targeting a velocity similar to what you are getting now at 1000psi, I expect all you'll need to do is tweak the hammer spring preload with an RVA.
Just to say.Use "next step" as if there is a final goal you want to reach. If you let us in on that final goal, would be a lot easier to figure out if a regulator is the "next step" or a step backwards.I really do try to keep some goal in mind when I set out to mod and airgun. Could be more shots per fill, could be more energy per shot, could be more accuracy, could be more stable POI, etc. Generally, will try to have something I'm trying to reach before I start twiddling around with the innards.
A Disco tube is 0.436 CI (7.1 cc) per inch, but the valve is a couple of cc's, and you will want to drill out the gauge mount or use a PRod mount (my choice), which will be another couple of cc's, so if you do that a 1" long plenum (assuming full diameter) should be enough for a 12 FPE gun.... I would use a piece of thinwall aluminum tubing for the plenum spacer, and you will have to follow the instructions with the regulator for a bleed hole.... You may have to make the spacer longer than an inch if the wall is a significant thickness, but of course there may be a plenum space in the regulator.... You are pretty much going to have to wait until you have all the parts to decide how long to make the spacer.... You can get away with a plenum as small as 1/2 cc per FPE, but you will have to add about 100 psi to your setpoint to allow for the loss of power.... and you will still not get the efficiency you would get with a larger plenum.... On the other hand, going larger than 1cc per FPE will gain you so little in efficiency it is unlikely to make up for the decrease of reservoir volume....Bob