Will a 300RUM fit in a 300WSM?


New Member
Jan 14, 2011
My brother has a habit of jamming 20 gauge shells in 12 gauge barrels etc., I have recently purchased a 300 RUM and my brother has jammed a shell into it and I'm I can't tell which shell he jammed. So will a 300 RUM shell fit in a 300 WSM and vice versa, I have 300 WSM shells, 270WBY Mag, 7mm mag shells, but I'm pretty sure it is a 300 WSM shell.

Any help?

Varminator 911

Well-Known Member
Dec 7, 2007
SW Texas
A 300 RUM should fit in a 300 WSM chamber but will be about 0.75 inch short of being able to close the bolt. So that combination wouldn't be dangerous.

A 300 WSM might fit in a 300 RUM but the base is 0.005 bigger on the WSM so it would be a very tight fit and hopefully the bolt won't close. That one if fired might be dangerous as the bullet would be about 0.75 inch short of really being into the throat. I won't want to try that combination.

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