Difficulty swaging Win 223 brass

[hddeluxe]

I tried the search function and could not come up with anything specific enough to answer my question, so I am putting it out to the members for some guidance.
I have been reloading for an AR (.223/5.56) for about a year now, and I recently (last night) ran into a problem I have not had before. I have been using a Dillon Super Swager for the brass that has been crimped and it has worked fine. Then last night I started swaging a batch of Winchester 223 (once fired from a military range) and encountered an extreme amount of resistance to the swage rod going into the primer pocket. I mean an extremely tight fit requiring a lot of force for both insertion and extraction of the swage rod.
I backed the guide rod off a little at a time, but it hasn't seemed to help. Primers seem to seat in the pocket with no felt resistance after swaging leading me to believe the pocket is now on the verge of being too large.
Has anyone else encountered this problem.
I have not swaged Winchester brass before last night. All my other brass is of different head stamps.
Am I doing something wrong?
Thanking everyone for any answers in advance.

 

[rg1]

I use RCBS's swager. I have ran into lots of WCC brass with heavy crimps making them harder to swage and to pop the swager out of the pocket. On particular lots of hard to swage brass I hit them a little with my deburr tool in a drill before swaging. I know, a lot more work. Also a little case lube on the swage tool every few cases helps. Off center primer pocket crimps makes them harder too.