Bad die?

[z28z34man]

I bought a set of Lyman 454 Casull dies off of a member here and some once fired brass from another member. When sizing the brass it was a little difficult to size and I had several split then I noticed it built up some brass strings Infront of the carbide sizing ring. I thought that was a little weird but oh well. I just got my Lee case length gauge and went to try to trim and the gauge won't fit in the case mouth. I miced the case and it reads .472. The book shows .4775 od. Is this normal and I need to sand down my case length gauge or is the die over sizing the brass

[z28z34man]

Just went and double checked it seems that it is just CBC magtech brass that won't fit the trimmer. That was the brass that I got the most of and scrapped out the least for cracking. The Hornady and star line work with the trimmer just fine.

[country gent]

Most dies over size then the expander sizes back up to desired size, this is so the diffrences in neck thickness of the brass don't affect the rounds. The "brass strings" you mention may be due to a sharp edge on the edge of the die, a little time with some polish and a marble or brass ball working the edge of the carbide ring to break the edge may help with this. You can polish the die out so it dosnt size as much but polishing crbide and removing any real material requires diamond lapping compound. I would deburr smooth the edge and use it. The case gauge could be polished down to just fit the sized cases easier.