Anybody build a big 7mm to shoot light bullets?

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by jayph, Oct 4, 2010.

  1. jayph

    jayph Member

    Jun 7, 2008
    I am tossing around the idea of building a slow twisted 7mm RUM to shoot the 120gr ballistic tip or similar bullet. Just a fun gun to blast a few chucks or out of fur season problem coyotes.

    If you have done it I would love to hear how it worked out. I am undecided on reamer specs, barrel length, and twist. I have also thought .300 RUM with 125gr bullets but the 7mm has a slight edge in BC.

    Any thoughts or advice?


  2. Varminator 911

    Varminator 911 Well-Known Member

    Dec 7, 2007
    The advantage of the RUM cases is with heavy bullets, long barrels, and slow burning powders. They can be hard to get them to shoot with the light bullets. At least this is what I've heard.

    There was a lot written on here a few years back about loading the 300 WSM with the 125 BT. Supposedly getting near 4,000 fps. But I believe most thought that could only be done at unsafe pressures. But If you need to do this at 7mm or 308, the WSM case would be better than RUM, in my opinion.

    For my taste a 243 loaded with a 55-87 grain bullet would be nearly as fast, or faster, and cheaper to shoot. The 243 shooting a 55 grain BT at 4,000 fps is a blast. The BC of that little bullet isn't up to the 125 BT, but these are really only medium range loads anyhow. Out to 300-400 yds the BC doesn't make much difference.
    Last edited: Oct 5, 2010