I decided that since most of my 300 Wby Brass is empty I would trim all ~ 150 to length and would leave the trimmer set and fire the ten that are loaded and trim them too.
Since I have ~ 150 cases I have not done this in twenty years.
So two cases obviously have the shoulders pushed in like if you tried to crimp the case mouth into a bullet w/o canalure.
So I checked my seater just to be sure and it is just fine. I use a Lee Collett die and it is just fine too. All I can think of is that I goobered these up by having the seater die wrong set years ago and pulled the bullets and fired & decapped the primers then ran them into a FL sizer die. These two were from a box of twenty that I actually use.
I doubt my RCBS FL sizer would do this but I backed the lock ring off so it is obvious it needs to be set next time I use it.
I shoot two or three rounds/year and then hunt w/this rifle so it is not like I am handling the brass all the time like on varmint rifles.
Any other explanation?

??
Here is what is really curious too, all the brass was long, real long and to the best of my knowledge I have only used forty of them to load and shoot. The rest is all once fired range pickup that was given me by a friend who lives at the range and he put it back in the new looking original Weatherby & Remington box after fishing those out of the garbage can at the range. I trimmed my original cases last about ten years ago and I would say that it has been reloaded an outside max of three times and it was real long too.
I don't pay a lot of attention to this 300 Wby brass even though it is my "go to" big game rifle. I shoot a modle 70 243 Heavy Varmint enough that I don't bother "familiarizing" my self w/this particular rifle. A Model 70 is like a part of me after shooting at chucks all summer and besides I don't like being beat up. Shooting Ithaca 37 bird guns means that when I am deer hunting w/a Deerslayer I don't have to have my neck stretched out and my shoulder beat black and blue shooting slugs off a bench at the range to have a Deerslayer be like a part of me too.
I'm kinda stumped on this shoulder thing though, unless it is like I surmise and I buggered up those cases and then pulled the bullets. The heck of it is: Now I don't trust any of the twenty cases in that box and think I am going to have to load up some el cheapo bullets and fire all of them just to be sure that these two are unique. I am way to cheap to just crap can all twenty.