For the past few months I've been shooting a Springfield Combat Operator, which is in 9mm. Its my first 9mm 1911. I have moderate experience tuning and running .45 1911's and understand the basics.
The Combat Operators come with a nice bar stock extractor, but the thing had no tension on it from the factory. Gun ran but ejection was erratic, including the odd brass off the forehead. I did my usual light polishing on the front lobe, and retensioned the thing to what I'd call "medium." Gun runs fine (not more brass to face) with a mag in it, but chokes every round without a mag in the gun.
I put a little more tension on it, its now a pretty firm fit; holds the casing flat against the breech face and the slide can be rotated at all angles without it falling out. Gun still runs fine with a mag, and I got 2 out of 10 rounds to eject properly (nice arc to the 3 oclock) without a mag in it, but the other 8 choked, sideways stovepipes.
I'm hesitant to put even more tension on this fucker for fear its gonna start inducing feeding issues. I've never had to tension .45 guns to this point to get them to run properly. Is there something specifically about the geometry in a 9mm gun that needs additional attention? Is the 10-8 extractor test not viable on a 9mm gun for some unknown (to me) reason?
Thanks in advance for any insight.