300 RUM Bullet Seating Depth?

Discussion in 'Reloading' started by MontanaRifleman, Feb 20, 2009.

  1. MontanaRifleman

    MontanaRifleman Well-Known Member

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    I just got a Sendero 300 RUM and I'm totally new to the cartridge. I've read some post that indicate it is a freebore cartridge. I'm not sure I totally understnad what free bore is, but this is my undrstanding... freebore is where the throat of the chamber is lengthend to provide a certain amount of space between the bullet and the rifling and one reason for it is to reduce pressures. If I'm wrong please correct me. Any links to diagrams would be great... I'm a picture kind of guy :D

    OK, based on the above, how should I seat my bullets? My philosophy in general has been to seat them just off the lands. Some bullets, like TSX's and E-Tips like a little more of a jump. Some bullets, like VLD's seem to like touching or seated into the lands.

    Would like to hear what you 300 RUM loaders are doing.

    I'm planning on trying out...
    180 E-tips
    177 GS HV's
    180 TTSX's
    180/200 AB's
    210 Bergers/JLK's

    Your experience and advice is greaty appreciated as well as any other 300 RUM knowledge.

    Thanks in advance,

    Mark
     
  2. J E Custom

    J E Custom Well-Known Member

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    Mark
    If you are going to load into the magazine ( for quick follow up shots )then you will have to
    load about 1/16 of an inch shorter than the magazine length.

    If you intend to single load then each type of bullet will/should be seated to different overall
    lengths based on bullet ojive.

    And yes the RUMs have freebore but so do a lot of other cartriges and if you use VLD type
    bullets the lands will be hard to reach and still maintain one caliber of ingagement in the neck.

    Don't let the freebore concern you the RUMs shoot extremely well with factory chambers .

    J E CUSTOM
     

  3. Derek M.

    Derek M. Well-Known Member

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    Powders: Retumbo, Re25, H1000, Ramshot Magnum, Re22.

    200 AB over Re25 in my rifle is a really nice kickass load. Lots of power, shoots really flat. My Shilen bbl is 28" long.

    180 Scirocco over either Retumbo or H1000 are also excellent combos that I've tried. In 2003 while in Colorado, I was shooting at an old archery foam target at 300 yards to test the rifle and ammo prior to hunting. The exit holes in the back of the target were a little bigger than golf ball size and the hole in the ground was a bit bigger. This combo is absolutely devistating on game.
     
  4. MontanaRifleman

    MontanaRifleman Well-Known Member

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    J E, yep, I plan to load for the mag so I'm guessing I will be well off the lands for that. One idea I have is to load for short and med range shots with the E-Tips or TTSX's, depending on which shoot the best and them work on a LR load for for farther out. My hunting style includes a lot fo walking and occasional sit and glass across canyons, etc. In this type of hunting I might encouter closer shots and might need a quick follow up. For the longer shots there will likely be some time to single chamber an LR load. Idealy, it would be nice to have one load/bullet for everything, but unless I get a longer mag, that might not be very practicle considering the LR type bullets will likely require seating too long for the mag.

    Which brings up another question... anyone know if the 700 can be modified with a mag for longer cartridges? And if yes, can I do it myself or is best done by a smith?
     
  5. MontanaRifleman

    MontanaRifleman Well-Known Member

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    Derek, Retumbo and H-1000 are top two powders on my list, in that order. Have read good things about them in this cartridge.

    Regards,

    Mark
     
  6. ejones338

    ejones338 Well-Known Member

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    It can be modified for longer mags, but a smith would have to do it, because for any thing worthwhile some metal will have to be machined from the action at the back of the magazine to accomodate it. I don't have the specs., but a friend of mine is having an edge built and this is being done to his rifle.
     
  7. ejones338

    ejones338 Well-Known Member

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    By the way, good choice on the new rifle. I just dropped the cash and ordered a sendero sf11 in .300 ultra this morning.
     
  8. RockyMtnMT

    RockyMtnMT Official LRH Sponsor

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    ejones338,

    Sent you a private message.

    Steve
     
  9. terrier72

    terrier72 Active Member

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    190 grain match king and H1000