The 9mm setup worked but the 20lb spring is too much for proper ejection even with the Underwood.
Remington 115gr FMJ Hunter 6": 1166, 1220, 1163, 1160, 1185, 1198. Average = 1182 FPS/ 357 LBS
PPU Partizan 115gr FMJ Hunter 6": 1285, 1231, 1218, 1237, 1215, 1236, 1257. Average = 1239.85 FPS/ 393 LBS
Underwood 115gr Gold Dot +P+ Hunter 6": 1540, 1565, 1532, 1519, 1527, 1530. Average = 1535.5 FPS/ 602 LBS. About a 65 FPS increase over the 4.75" Limited barrel. I guess if you have a 4.5" -4.75" barrel you are getting about all you can out of 9mm rounds.
I suppose there is a lot of mass to the slide therefore a weaker recoil spring would allow extra velocity of the heavy slide for more reliable extraction/ejection. Its all about balance vs. impulse. ???
It was set up to run the 10mm and had everything going against rounds not even same ballpark. It has the flat bottom block in it too which makes things even tougher. With the Underwood it would probably work fine with a 14lb spring and the others the 11lb. Hopefully Thursday I will venture back with it and try the 11lb spring.