01/27/2021 (Wed) 07:38:16
Steel case is notorious for sticking to chamber walls, and having to be knocked out with a cleaning rod, or even pulled out with pliers in the worst case scenarios. Something I've actually had to personally do.
Bi-metal casings are always heavily coated in a lacquer/lube finish to help them load and extract. And even some brass is. 5.7x28 especially so. It's one of the things that actually makes reloading it slightly more difficult than others. Most people advice tumbling 5.7 brass more than you would any other, to keep them as smooth as possible.
So I can't imagine steel cased 5.7 being very... pretty, in that department. One reason I asked if you had any stoppages with your steel cased 9mm.