What are the Long and Short Tolerances for Brass Case Length in Reloading?
Reloading manuals show a picture giving the case length, for example, a .45 cal. ACP case is .898″. These manuals; however, give no general rules for tolerance. Some may state the maximum acceptable length, but not the minimum length.
Reloading manuals give a maximum length and a trim-to-length. I have several manuals, they all give this. On bottleneck rifle cases the trim-to-length is typically .010 below maximum length.
I have never needed to trim a .45 ACP case
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Fallout New Vegas Reloading Guide