I know a lot of guys use range brass, I did for a long time too but stopped a few years ago because I encountered significant problems. However, with today's shortages, I understand the need to retrieve range brass and I'm not going to condemn it.
However, this could be the source of your problem if it is indeed a problem. Like I said, if the cases chamber and extract without issue and you have no pressure signs, I don't believe there is a reason to address the bulge.
I have several 223 Rem bolt rifles of different brands, twists, etc. Some have after market custom barrels. A few of these factory rifles exhibit isolated case bulging at the base. However, functionally the affected cases perform without incident. Also, I can detect no affect on precision with these cases. I typically get about 15 to 18 reloads on these cases which are full size with a slight shoulder bump.
I found that dedicating a group of cases to a specific rifle and rotating their use aids greatly in consistency. Also, starting with virgin cases helps a lot.
When it comes to semi's - I will defer to others since I do not shoot or load semi's. I do believe that the small based dies were developed for semi's, not bolt rifles but I don't have any experience reloading for semi-rifles. The last time I shot one was in the Army, in 1970.