I just opened up the transfer ports to 7/32 yesterday and got to test it this morning. Little disappointed to be honest. Only picked up about 25 fps on average and maybe 4 fpe. This is at max stock setting on regulator and hammer spring. I'm guessing there is another bottle neck somewhere I don't see. I'm just about at 60 fpe which is decent but I was thinking I would be closer to 65-70 after the port.
I was touching 55 FPE in stock form. Leads me to believe the barrel port may not help without the transfer port being done as well. The plenum itself didn't seem to help with more power but did allow for lower regulator pressure to attain same speeds. I am just barely under 60 FPE now but that is with jsb 33.95 pellets. Hoping some slightly lighter slugs will allow for more speed and power.
Everything is pretty easy to get to honestly. Take off front picatanny rail and you will see 3 set screws holding the barrel in place. Unscrew those and slide barrel out. The back set screw is much larger than the others. If you look down that threaded hole you will see the transfer port on the other side. Unfortunately you have to drill out the top threads to open up the bottom port. However I just ran a 1/4-20 tap on the top and got a 1/4" set screw to replace the smaller one and secure the barrel. I started another thread with my results but I believe the most improvement comes from enlarging the bushing that the poppet goes through along with a lighter spring. I saw huge gains doing that.
I'm not sure on those sizes. I bought the plenum on ebay who I believe is a member here as well. Though if you have all the equipment it appears like it wouldn't be too hard to make.
And DOWN the rabbit hole you go. Don't worry about hitting bottom, there isn't one. Welcome
Ha I have already maxed the gun out it seems. Next up is to tune my preferred pellet to perfection and try and find a slug the gun likes.
Maxed out at 77 FPE so far. I think this may be too much power for this gun but we will see. The 33.95 pellets seem to prefer to be below 880 FPS but that is not in stone yet. I will have about 10-12 different slugs to sort through to find the best. My goal is to find a slug I can shoot at around 70 FPE and be accurate. If I can't then I will just have to deal with shooting only pellets at 60 FPE and under.
