Well, today was kinda wierd.... I took the rifle all apart and matched up all the ports to smooth and maximize the flow.... I ended up with a 0.180" valve top port, 0.183" transfer port, 0.185" through the breech, and a 0.187" barrel port.... I polished the barrel with some bore paste and stuck everything back together and gained a whopping 6 fps (0.5 FPE) for my trouble.... but at least it didn't use any more air, so the efficiency was a solid 1.20 FPE/CI.... Basically all the ports downstream of the valve are as big and smooth as I can go.... By now I figure the choke point is the valve seat itself.... It looks like this....



There was a spare supplied with the parts that came with the gun, and it measures 0.171" ID, less the area of the 0.100" stem.... so the equivalvent area is the same as a hole measuring 0.139" (the same size as a stock Disco transfer port).... This is obviously a lot smaller than the rest of my ports.... I figured if I ruined the seat I had a backup, so I knocked it out of the valve and measured it.... and found that the hole in it was even smaller than the spare, it only measured 0.163" ID.... I mounted it in the lathe, and using my number drills, one at a time, slowly took it all the way to 0.187".... the same size as the ports (but still less area because of the stem).... The throat area is now the equivalent of a 0.158" hole, 50% larger area than the one I took out.... There is enough meat to drill the hole out to about 0.200", and I can thin the stem down to 0.090", and match the throat area to the area of the rest of my ports if I need to.... However, I know that if I make the valve too big, the hammer may not open it.... so I stopped at 3/16".... stuck the gun back together and shot some more strings....

WOW!.... What a shocker.... I still had the hammer preload at 7 turns out, hoping that it would have enough oomph to knock open the larger valve at 200 bar.... Well, the first shot over the Chrony was 990 fps, then 1010, and it peaked at 1023 fps before falling back to 983 at shot 15.... Drilling out that valve seat gained me 75 fps and 8 FPE.... and the hammer still worked !!! .... I dialed the preload down to 6 turns, and then down to 5, and the gun was still shooting way stronger than before.... I set the preload back to 7 turns out and shot a string with H&N Baracudas and EunJin Domes.... Here are the results....



The dotted black lines on the graph are from the first string today, JSB Kings at 7 turns out, before I drilled out the valve seat.... That was the most power up until today.... The red pressure line can be used for all the pellets at 7 turns preload.... Here is a summary of the results:

25.4 gr. JSB King: 1023 fps (59.0 FPE) max.
1009 fps (57.5 FPE) average for 15 shots @ 1.06 FPE/CI

30.9 gr. H&N Baracuda: 957 fps (62.9 FPE) max.
944 fps (61.1 FPE) average for 15 shots @ 1.13 FPE/CI

35.2 gr. EunJin Domed: 915 fps (65.5 FPE) max.
899 fps (63.2 FPE) average for 15 shots @ 1.17 FPE/CI

That's a 9-10 FPE gain over yesterday.... The shot count is a few short of the 18 (two full clips) that I want.... but my power goal of 50-60 FPE has certainly been achieved.... and by enough margin I am confident that I can get an 18 shot string in the 950 fps range with any pellet from 25-31 gr., and that includes all the ones with a decent BC....

It's been quite a day.... Using JB Weld on the groove in the valve will have to wait, the tubes I have are so old they are hard as a rock.... Tuesday (after the holidays) strangely seems a long way off.... but I'll enjoy the weekend knowing I've accomplished my goal with this rifle....

Bob