Don't be too aggressive deburring the case mouth when you have not trimmed the cases. When you trim the cases you must deburr the brass edge which has formed inside the case mouth. A new case can be chamfered slightly, but with a case which is to be belled, deburring is unnecessary. A straight wall case does not seem to lengthen as quickly as a bottle neck case, and often trimming is most useful to remove small cracks which sometimes form around the case mouth. The .45-70 accepts bullets easier if you bell the case mouth and this should be sufficient with new brass.