Hello AirgunNation Peoples,
Yes I did!
There it is, I designed and created a 2” plenum spacer as a modification for my FX Dreamline .22 caliber - Bullpup! I won’t call it a “power plenum”, but that is exactly what it is! It works and I will tell you all about it. Here she is all finished!
Back Story:
First off, my DreamPup .22 caliber has already been modified and tuned to shoot slugs. With (prier to the 2” plenum extension) a 600 mm FX slug “A” liner barrel and shroud, a hammer spring tension increase modification, and the AMP regulator set @ 145 bar. This previous setup and tune gave me around 900 fps and 41 fpe shooting Nielsen Specialty Ammo 23 grain hollow-point slugs. Check the chronograph string below this was all the energy I could get out of her.
Inspiration:
The idea was inspired by the Huma-air regulators I have installed in my FX Wildcat and Streamline. You see, due to the location of the two guns I mentioned regulator vent hole (on the air cylinder tube) and the Huma regulator’s smaller more compact size, the regulator must be installed with a small “plenum spacer”. See picture?
Analysis:
So I thought about it and posed the question to myself... “What if that plenum spacer was bigger”? That would result in more regulated air aka a “power plenum”! But, if I installed this larger plenum spacer, the regulator vent hole would not be in between the AMP regulators o-rings where it needs to be..
Thinking
....
GOT IT!!
I will order the 2.5” longer 290cc FX Dreamline .25 caliber air cylinder tube and measure and drill my own regulator vent hole / AMP regulator adjustment access hole (the .22 DreamPup’s air tube is 220cc). I already have the longer 600mm barrel in .22, so fitment won’t be an issue. It ultimately will look like a .25 caliber DreamPup.
Modifications:
I made my 2” plenum extension from 1” OD .049” thick aluminum pipe / tubing (similar to the Huma’s). Once my 290cc air cylinder came in the mail I went to work. Pictures explain.
Done! It worked with no leaks!!! The airgun now has about twice the plenum volume and about a half an inch worth more air space on the high pressure non-regulated side! Time to tune.
Tuning:
Here comes the amazing part, an additional 2 inches of regulated plenum air for a Dreamline is magical! Increased plenum size benefits are not hype. I am now able to achieve more power with less regulator pressure. Remember earlier I said that previously my AMP regulator was set at “145 bar”, and topped out at “900fps” with 23 grain NSA’s? Well, now it’s set @ 122 bar and she’s shooting 930 fps for 44 fpe! That’s 23 bar less AMP regulator pressure, and that naturally equals more efficiency!! Check it out?
Accuracy:
This DreamPup was a tac-driver before this modification, but there is something about a lower regulator pressure that just feels / sounds smoother and cleaner per shot. As opposed to a high pressure regulated air blast. I plan to post pictures for groups at longer yardages later, due to weather I only put on paper this 10 shot group at 25 yards using NSA 23 grain HP slugs. (for now)
Conclusion:
I’m proud of myself and this airgun! To transform this DreamPup from a 30 fpe pellet shooter to a 44 fpe slug gun is a accomplishment. Not to mention, it still can fire pellets at practically any velocity or energy I want with a turn of a hammer spring or transfer-port knob. She powers up or down. I feel that larger plenums from the factory will begin to be a normal factory engineered thing. There is just to many benefits, because this FX DreamPup is now my best .22 caliber airgun I own. On the outside you can’t even tell a difference but it’s what’s on the inside that counts!
Appreciate it Peoples,
JoeKool
Yes I did!
There it is, I designed and created a 2” plenum spacer as a modification for my FX Dreamline .22 caliber - Bullpup! I won’t call it a “power plenum”, but that is exactly what it is! It works and I will tell you all about it. Here she is all finished!
Back Story:
First off, my DreamPup .22 caliber has already been modified and tuned to shoot slugs. With (prier to the 2” plenum extension) a 600 mm FX slug “A” liner barrel and shroud, a hammer spring tension increase modification, and the AMP regulator set @ 145 bar. This previous setup and tune gave me around 900 fps and 41 fpe shooting Nielsen Specialty Ammo 23 grain hollow-point slugs. Check the chronograph string below this was all the energy I could get out of her.
Inspiration:
The idea was inspired by the Huma-air regulators I have installed in my FX Wildcat and Streamline. You see, due to the location of the two guns I mentioned regulator vent hole (on the air cylinder tube) and the Huma regulator’s smaller more compact size, the regulator must be installed with a small “plenum spacer”. See picture?
Analysis:
So I thought about it and posed the question to myself... “What if that plenum spacer was bigger”? That would result in more regulated air aka a “power plenum”! But, if I installed this larger plenum spacer, the regulator vent hole would not be in between the AMP regulators o-rings where it needs to be..
Thinking
.... GOT IT!!
I will order the 2.5” longer 290cc FX Dreamline .25 caliber air cylinder tube and measure and drill my own regulator vent hole / AMP regulator adjustment access hole (the .22 DreamPup’s air tube is 220cc). I already have the longer 600mm barrel in .22, so fitment won’t be an issue. It ultimately will look like a .25 caliber DreamPup.
Modifications:
I made my 2” plenum extension from 1” OD .049” thick aluminum pipe / tubing (similar to the Huma’s). Once my 290cc air cylinder came in the mail I went to work. Pictures explain.
Done! It worked with no leaks!!! The airgun now has about twice the plenum volume and about a half an inch worth more air space on the high pressure non-regulated side! Time to tune.
Tuning:
Here comes the amazing part, an additional 2 inches of regulated plenum air for a Dreamline is magical! Increased plenum size benefits are not hype. I am now able to achieve more power with less regulator pressure. Remember earlier I said that previously my AMP regulator was set at “145 bar”, and topped out at “900fps” with 23 grain NSA’s? Well, now it’s set @ 122 bar and she’s shooting 930 fps for 44 fpe! That’s 23 bar less AMP regulator pressure, and that naturally equals more efficiency!! Check it out?
Accuracy:
This DreamPup was a tac-driver before this modification, but there is something about a lower regulator pressure that just feels / sounds smoother and cleaner per shot. As opposed to a high pressure regulated air blast. I plan to post pictures for groups at longer yardages later, due to weather I only put on paper this 10 shot group at 25 yards using NSA 23 grain HP slugs. (for now)
Conclusion:
I’m proud of myself and this airgun! To transform this DreamPup from a 30 fpe pellet shooter to a 44 fpe slug gun is a accomplishment. Not to mention, it still can fire pellets at practically any velocity or energy I want with a turn of a hammer spring or transfer-port knob. She powers up or down. I feel that larger plenums from the factory will begin to be a normal factory engineered thing. There is just to many benefits, because this FX DreamPup is now my best .22 caliber airgun I own. On the outside you can’t even tell a difference but it’s what’s on the inside that counts!
Appreciate it Peoples,
JoeKool
