300 Blackout Brass Processing Issue

[rlandry6]

This is strange. After sizing, chamfering , and beveling case mouths, I still have a very slight lip on the outside of the case mouth. It almost looks like it was flared.
Here is my equipment and workflow.

Brass is all LC, cut on a Harbor Freight chop saw
Sized on a T-7 press, RCBS Small Base die
Checked headspace in a Sheridan Slotted Gauge. All Good so I know I'm not crushing the case when I size/form it
Lyman Case Prep center that deburrs the flash hole, cuts the primer crimp and squares the primer pocket, chamfers and bevels the case mouth
Trimmed on a Wilson Case Trimmer to 1.358"
I use an expander mandrel so the sizing die does not have an expander ball

I do tend to get a little aggressive with the trimmer just to insure I get a square cut and the case gets trimmed to the proper length, but I can't imagine that I'm putting enough pressure on the cutter to deform the case mouth. I went back and checked some previously processed 300 brass and those cases are OK. They were sized on a different press, but everything else was the same except it was once fired brass.

A little more info. This is brass that was originally processed for a .20 Practical. It required sizing the neck twice using two different bushings. The case necks were a little knarly looking after the double sizing. That's one reason I sold the barrel and built a different caliber rifle, I just did not like the looks of the finished brass.
As I write this, I'm starting to think that I may have caused my own problem trying to reuse that brass.

Thoughts from you reloading gurus?

[Sig220]

Can you post a pic?

[rlandry6]

I may have found my problem. Since the last time I used these dies, I ground down the expander ball so I could use an expander mandrel and still retain the decapping function. It looks like I didn't grind it down enough and the expander ball was loose on the threads. I can't figure how that would cause the problem, but I corrected everything and processed a dozen or so cases and everything looks OK