.416 application, 300 RUM vs. .375 RUM brass?

Discussion in 'Reloading' started by nw07heavy, Apr 4, 2015.

  1. nw07heavy

    nw07heavy Member

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    Mar 3, 2012
    I have a question for those of you with .416-300 RUM, .416-375 RUM, or .416 UltraCat experience. Looking at the SAAMI drawings for the .300 RUM and .375 RUM cartridges I see that the outside case dimensions are identical, and the 30 degree shoulder beginning at 2.3873" is the same for both cases, which would indicate that either case would be suitable for loading a .416 bullet into standard RUM cases, once the length reaches 2.4540 and the neck begins. My question is whether they would reload and function equally well. I understand the .375 RUM cases would be less trouble than the .300 RUM to neck up to .416 due to needing less size increase. Is there something I am missing in regards to this brass, possibly neck thickness? I also noticed that reloading dies come in designations of .416-300 RUM, .416-375 RUM, and .416 UltraCat (all appear to have the standard RUM dimensions) and wondering what the functional differences are between these designations, and subsequent selection of reloading dies. Thanks for any insight you can provide.