Well, the project started out Saturday morning with a 45 minute drive up to my friend Rick’s machine shop, which would normally be an hour+ under non-Covid circumstances, with the day shaping up to be about 70*.
After Rick and I took off the aluminum shroud and laid out all the new pieces and 20mmX18mmX1000mm carbon fiber shroud he had this great idea. "Why not use both compensators stacked and make kind of a longer baffle. I said “let’s give it a try”.
The stock aluminum shroud is 585mm. We cut the CF to 628mm to accommodate the additional compensator length.We put the stock 1/2x20 compensator and 585mm shroud in a ½ collet in a vice and heated the tube to break the FX adhesive and remove the compensator. Nice and hot with the heat gun and no problem.
Then we used the same ½” collet to hold the tail piece of the compensator and turn down the coller and threads to match the ½” O.D. to allow the gas flow of both to the shroud, then screwed them together. We contemplated whether to have the slots parallel to each other or 90*. We chose parallel and faced the inside compensator to do so. Also, sized down the threads on both end pieces to slip perfectly into the 18mm I.D.
Because we knew we might have to make adjustments to this “experiment” no adhesive was used.
Assembled everything and added my new FX barrel band and was ready to test!!
Rick has 15yds to shoot in and a nicely housed sand trap for a backstop. First couple un-suppressed shots with the 34g JSB were promising and a re-zeroing was barely a couple clicks away. Adding the Donny FL changed everything. POI was everywhere. What??? We assumed pellet clipping and we found a couple spots at the end of the shroud compensator and by the time it left the suppressor it surely had clipped a few more baffles. The FPS was still consistent from my previous testing with the new Plenum @ a 4% increase in speed over non-plenum, both with no adjustment from the factory. Some pellets were hitting the target sideways due to clipping. We made a lot of adjustments up to this point and needed to figure where the problem was originating.
We moved the barrel band up and down the shroud, took off the FX shroud stiffener, tried a Donny Sumo too, took off the barrel band, added back my o-ring to the barrel for front droop, adjusted my felt strip on the fill cap that kissed the barrel end for added droop support… And various combinations of these. No love.
Rick said we should bore out the compensators and see where that takes us. Reamed, then Bored the compensators .100 over and continued testing. Un-suppressed groups were OK but not as great as factory, but better than before. Suppressed shots were still shotgun ¾”. Not impressed.
Back to square one.
We decided to cut the carbon fiber back to 585mm with the single compensator (now with bigger bore), FX barrel stiffener and FX barrel band.
Dreamline shoots Lights-Out now, pellet on pellet with or without the suppressor. Much tighter than factory. Sound is a little lower in pitch, not so tinny.
Our conclusion: The extra compensator used as a baffle was causing to much turbulence in the baffle area just beyond the barrel and causing pellet instability. The extra bit of backpressure in the suppressor added to it and aided in the clipping. All this is pure theory on our part.
Was it worth testing? Absolutely.
What I have now is a Dreamline plenum with a really nice looking carbon fiber shroud that is lighter than the aluminum (about ½), an FX barrel stiffener and FX barrel band. 10/10 in 10mm @15yds is a good benchmark for me to now actually tune the gun to my 34g JSB’s
I’m a happy camper.
Thank's to Rick for his time and expertise.
