I need to trim unfired .375 H&H winchester brass. Many of them have case mouths that are out-of-round so that I am having trouble feeding the case mouth unto the trimmer pilot. My question is to trim and then size the brass or do it where I size and then trim. Neither way is going smoothly because of the fit of the case mouth unto the pilot. The fit seems tighter if I resize first unless the casemouth is dinged. The pilot measure .370 in diameter. I have never trimmed brass the large before and would like any advice that you could give to me.

Thanks in advance.

Ron I am just over the hill from you. I am in Jackson county. You need to resize it first. No telling how much you trim off on one side and not on the other if it is out of round. Good luck with the 375. It is my favorite round for all around use. If you get into other 375 questions e-mail me.dsmbus@gte.net I am not an expert but have loaded for it quite a bit over the last 3 years. Made most of the mistakes already.Good loading and hunting. "D"

Resize them first and make sure you use some lube on the inside of the neck as well as the outside of the case. I use a kit from NECO that has steel balls with graphite in a box...just dip the neck in the box and you're good to go.