An updated. I replaced the extractor, depressor plunger, plunger spring and bearing. This corrected the problem of my brass collapsing at the case mouth. None of the old extractor components appeared to have any obvious defects or damage. The new spring did seem to be of a stouter construction. I think I got a little tunnel vision on the problem as it happened while working up a load.

Thanks for the help

The gun is a stock G20 Gen2. The gun should have been fairly clean when this happened and has not been fired since. I will run some factory loads thru it this weekend and see what happens as I did not have any factory ammo with me at the time when the case denting occurred. Never thought about trapping by the extractor. 

If the slide is hitting the brass what would be the root cause of this? I will do a control shoot with some SIG factory 180 grain I have that has always shot well in the gun.   

Thanks for the help guys. Got my image posted but I ended with a large one and I put in the reloading section by accident. It is a reloading post but was specific to 10mm. I'll get it together sooner or later......... maybe!

New member here. My last batch of reloads was a step up in grains of Accurate No7 but still under max. The bulk of my brass had a dent extending down from the case mouth about a 1/4 inch on one side. Looks like case is hitting ejection port. The gun is a stock G20 Gen 2. Brass is once fired SIG.

Load: 155 grain XTP
         12.4 grains Accurate No 7
         OAL 1.25

My previous load with Accurate No 7 was the same except with 12.0 grains. Both loads shot well and did not exhibit any obvious signs of over pressure. Any thoughts on what is going on and how to correct?   

Thanks. Sorry for large image. Still learning the ins and outs of image posting.

Complete fail in trying to link a image off Imgur.