I didn't expand the case mouth. All of the rounds I shot with the H4895 seem to seal the case mouth with little pressure flow back along the case so I didn't think that flaring was necessary. I have a 30 Wesson based on the 357MAX that needs to be flared as without the flair I would get leakage rearward to the extent of getting powder smudge on the bottom of the scope eye piece. I still have more testing as I have a fair amount of 4227 on hand and my 32-40's love it. I also have a few pounds of IMR3031 but next to nothing for IMR4198. Hope some more IMR4198 shows up on the market but I'm not going to hold my breath.
A. J. Palik