I haven't trimmed any of my 45-70 cases. Remington, Winchester, Starline. Some of the Winchesters with my squirrel loads have 7 or 8 loads through each brass. Remingtons have had some nearly max loads through them and haven't stretched, Starline I have loaded to almost 60 grain H4198 under a 300 grain bullet several times and no stretching there either.