Works best with new or once fired brass, Curl. I do it in one pass- with STOS or other lube inside the necks. I have 2 dies for doing this, one takes them to .420", the other to .410". If running .270's or .30's up straight,I have to use the smaller pointed one, while the more blunt plug will do .35Whelen brass. When making brass for my new .375/06IMP, I gathered up all my '06 brass, mostly RP and Fed, some WW, and ran them over the pointier plunger. I lost 8 cases in over 150 pieces of brass- easily worth while, due to the brass having been fired anywhere from once, to 8 times. Most of the older brass in RP brand survived. Although some guys swear at RP brand, I've come to like it in many calibres. WW has the greatest capacity, while RP and FEd are about the same and in this ctg. are interchangable, load wise. They have 78gr. water capacity, compared to about 80gr. or 81.0gr. for WW. Note the 2 1/2" magnums have something like 85/86gr. capacity. Our .375's have a .460" shoulder compared with most IMP .06's having a .454" shoulder. Note also, I am using the same loads in this rifle that I used in my first .375/06IMP and 9.3x62, both of which have .454" shoulders. What wonderful rounds!!!!!!!!!!!!