I started this project last year with the thought that a gas operated 9mm should be a smoother ride than the clunky blowback bolts, but is obviously a challenge. I reload 9mm major for USPSA, so ammo isn't a concern. I am currently running 7.0 of WAC with a 115 jhp. My first try had the gas system about 1.25" farther forward than it is in the pics below. It was decent, but the gun cycled too slow compared to blowback rifles. As a match gun it must be able to cycle quickly. I then started doing some more thinking and some research. That led me here with some past threads found through Google searches.
I've shortened the gas system about as much as I can figure how to do it. I'm getting plenty of gas and the gun runs fine, but still a couple of feed issues. I'm thinking I need to cut a ramp at the bottom of the barrel extension to smooth that out. Another problem is some cases aren't ejecting 100% and getting caught. I might need to open the bolt up a bit more as I just used a .223 bolt and opened it a little. Never knew about using a 5.45 bolt until a few days ago reading on here. Another problem is that using a Glock mag lower and the mag keeps getting sucked up into the upper and jams the bolt. I may need to glue a stop collar or something onto the mag to hold it in place. Any suggestions on this? I had to cut (grind) the bottom of the bolt carrier body and bottom 2 locking lugs to clear the Glock magazine feed lips. Anything I'm missing here?
shorty gas system. I turned the area for the gas block kind of an elliptical from the barrel to avoid severe bends in the gas tube.