[1911Tuner]

Could be short-cycling. Weak ammo or oversprung slide, coupled with a weak grip can do it. That would be the first place to look.

A guy came by here with a 9mm Colt Combat Commander with the same issues as you're having. The first thing I noticed was that the recoil spring was way yonder too heavy. I cut a 14-pound Government Model spring down to 24.5 coils and his ejection problems disappeared, even though it was still a mite bit oversprung.

Note that cutting a GM-length spring to work in a Commander will only work in Commanders with the standard recoil system. Bushingless/reverse plug setups will not work, nor will it fly with Colt Officer's Models.