Tuning Dialing in a new to me dreamline bullpup

[Noose]

I purchased a used FX Dreamline .25 bullpup. As I received it, it was set at 150 on the regulator. It has the power plenum installed. The transfer on .25/30 is at max FPS on 4 on the power wheel. If I go up toward max, FPS drops off. If I go down from 4, it drops off. I backed the regulator down to 135 and got the exact same readings as I did at 150 so I assume my hammer spring needs adjustment as I'm currently at max FPS and I am reaching a max of 823 fps for a 33.95 grain JSB. I'd like to see this pellet hit 860ish as I understand that is the sweet spot for this shaped pellet in this caliber.

As far as the hammer spring "stock" setting, what would be the approximate turns out from bottom? I'd like to get as close to stock tune setup as possible and dial it from there. I'm still having a bit of trouble figuring out hammer spring to regulator relationship but still reading. Any guidance would be appreciated.

 

[rappert]

I have the 30 Cal version of this gun with the power plenum also. I am pushing 44 gr. JSB's at about 893 fps and 49.5 gr. Nielsen slugs at 850 FPS, so I am confident you can easily get there with your 25 Cal with a 33 gr pellets once you work through your tuning issues. I'm running my regulator around 155 with hammer wheel on max. I'm not sure what you were asking about "approximate turns out from the bottom". That sounds more like the Dreamline Classic with the internal hammer spring plug that you turn in and out. As far as the lack of increase in fps with the hammer wheel at 5 and max: Since you got the gun used it might be worth pulling the external hammer spring adjuster off and slide the spring and hammer out and weigh the hammer to verify its weight to see if it is stock. Sometimes people will install aftermarket hammer/weights/ and hammer springs. I have no problem opening my valve with the reg at 155 and my hammer wheel at max setting. Also another thought: fx gauges have been know to be off considerably. In other words what you think your regulator pressure is, may not be what you actually have. Just another thing to check.i I replaced mine with a Wika gauge.

 

[Noose]

I have the 30 Cal version of this gun with the power plenum also. I am pushing 44 gr. JSB's at about 893 fps and 49.5 gr. Nielsen slugs at 850 FPS, so I am confident you can easily get there with your 25 Cal with a 33 gr pellets once you work through your tuning issues. I'm running my regulator around 155 with hammer wheel on max. I'm not sure what you were asking about "approximate turns out from the bottom". That sounds more like the Dreamline Classic with the internal hammer spring plug that you turn in and out. As far as the lack of increase in fps with the hammer wheel at 5 and max: Since you got the gun used it might be worth pulling the external hammer spring adjuster off and slide the spring and hammer out and weigh the hammer to verify its weight to see if it is stock. Sometimes people will install aftermarket hammer/weights/ and hammer springs. I have no problem opening my valve with the reg at 155 and my hammer wheel at max setting. Also another thought: fx gauges have been know to be off considerably. In other words what you think your regulator pressure is, may not be what you actually have. Just another thing to check.i I replaced mine with a Wika gauge.

Thanks - I'll look into replacing the gauge. Given I have the EXACT same FPS measurements at "150" vs "135" on the pressure gauge, wouldn't that make a difference if I was under-pressured at the regulator from it being off? My second comment and perhaps I'm wrong -- is there an internal hammer spring adjustment along with the external? I've watched a bunch of videos and read a bunch of posts and I keep seeing reference to both an internal and external but perhaps I'm mistaken.

 

[corny]

Not to familiar with the dreamline lineup. 
but from the little I’ve read, it appear ppl are shimming the Hammer spring or replacing it entirely with a stronger spring to gain more power. That would tell me the main spring isn’t adjustable like the impact line. 

By design, all u got is the power wheel. 


if it were me…i would tune it for a lighter pellet. I don’t like to max out a gun on the power level.

 

[Clifton]

I have an early Dreamlite, not pup in .25 using 34g JSB MKII's. I have a plenum and reg turned up to just under 150, max it goes on mine. I used a small shim on my hammer for added weight but it didn't do much. Hammer is adjusted to max. I had to port the TP and to get to what you are looking for. I am consistent 870-880 fps with 34g

 

[Noose]

Thanks, Clifton. I'll just keep it the way it is, I guess and move to a lighter pellet. I have about 1K of the Kings to burn up and then I'll go that route. I didn't want to get into a bunch of tuning but I had hoped the .25 bullpup with a slightly longer barrel and the plenum would get me to 860 or so. Maybe I'll try the shim. Maybe not. Either way, "4" on the power wheel and .25/30 on the transfer along with what appears to be 150 on the regulator is all she's got, then.

 

[Noose]

I have the 30 Cal version of this gun with the power plenum also. I am pushing 44 gr. JSB's at about 893 fps and 49.5 gr. Nielsen slugs at 850 FPS, so I am confident you can easily get there with your 25 Cal with a 33 gr pellets once you work through your tuning issues. I'm running my regulator around 155 with hammer wheel on max. I'm not sure what you were asking about "approximate turns out from the bottom". That sounds more like the Dreamline Classic with the internal hammer spring plug that you turn in and out. As far as the lack of increase in fps with the hammer wheel at 5 and max: Since you got the gun used it might be worth pulling the external hammer spring adjuster off and slide the spring and hammer out and weigh the hammer to verify its weight to see if it is stock. Sometimes people will install aftermarket hammer/weights/ and hammer springs. I have no problem opening my valve with the reg at 155 and my hammer wheel at max setting. Also another thought: fx gauges have been know to be off considerably. In other words what you think your regulator pressure is, may not be what you actually have. Just another thing to check.i I replaced mine with a Wika gauge.

I'd like to get a Wika - It seems there are a bunch of shapes/sizes as I google around. I'd like a black side/black face and obviously go to 250 with lines I can read instead of the one that is on it which doesn't have the granularity to get really exact measurements. Which one did you install on yours?

 

[rappert]

Noose,

I got mine at Utah Airguns WIKA 28mm 315 BAR Gauge (No Black Cover) | Utah Airguns you can add the black cover for an extra $10.

As far as the external and internal hammer spring adjustment: The DreamPup has only an external hammer spring adjuster (the wheel adjuster) and the Classic has only the internal hammer spring adjustment. 

As far as the "Given I have the EXACT same FPS measurements at "150" vs "135" on the pressure gauge, wouldn't that make a difference if I was under-pressured at the regulator from it being off?" Yes that is odd. That is why you should verify your hammer weight and spring is stock. You should be opening up you valve sufficiently to get upper 800"s FPS, especially in 25 cal and at 150 or below on the regulator assuming you really are below 150. 

 

[Noose]

Thanks rappert! I've disassembled down to the spring. While it appears stock, there's no way to really know, is there?. Maybe I'll just order a stock spring to be sure. In order to remove the hammer weight, I'll need to remove the sear so I'll have to get to that when I get a bit more time as I believe the only way to get that out is remove the screws/pins unless I'm mistaken. I'll order the Wika regardless as there are not enough gradations on the stock to get an accurate read and, as you say, it could be off.

I checked a couple of other things while I was at this point - the tiny little screw that slides on the lobe of the power wheel is set right at max so there's no slack there.

A shim obviously does nothing as I'm maxed out at 2 spots below MAX on the wheel and the shim would just "move" my sweet spot on the wheel. Assuming I was at MAX, then I suspect a shim might give me a little boost.

I'm learning as I go here and I sincerely appreciate the help.

 

[Noose]

Back for a quick update for anyone else that might be following. I reached out to FX to see what they thought. They told me to make sure that the micro adjustment on the little slider was as far as it could go without stopping the power wheel and to turn up my regulator psi a small amount and test again. They said I should reach 850-870 fps with the JSB 34s turned all the way up and that was without a plenum...

I will need to check the hammer weight also but haven't gotten to that yet.

I ordered a Wika and put that in but now the rifle won't fill as I have a leak around the plenum from flattened o-rings so I'm figuring that out now. I did get one of the FX "dreamline tuning springs" just in case the spring isn't stock or worn out. It doesn't really "feel" any stiffer than stock but we'll see once I get it on.

In hindsight, I probably should have just left it alone and moved to a lighter pellet as I now have cascading problems but 810-820 even with a power plenum seems quite a bit slower than I'd expect.