243 to 260

Discussion in 'Reloading' started by hunter966, Mar 20, 2011.

  1. hunter966

    hunter966 Well-Known Member

    Apr 29, 2009
    I just had my first custom made for me, it's 260 Rem. built on a trued Rem 700 action.

    I have several hundred pieces of 243 brass on hand and was wondering what it would take to size it up to use in my 260. I have a set of RCBS 260 dies but don't want to ruin them by running the 243 brass through them.

    What do I need to get to be able make the 243 brass useable in this 260 rifle?


    ICANHITHIMMAN Well-Known Member

    Jan 31, 2008
    Just run the 243 brass trough your 260 rem die and trim to length you should be fine. I also like to put some lube on the expander and a bit around the inside of the neck

  3. RT2506

    RT2506 Well-Known Member

    Jan 10, 2008
    For my buddies 260 Rem that he got waaaaaay back before you could even find any ammo or any load data was out we made our cases out of 243 Win because it would give you the proper neck length over 308 cases. We just sprayed the cases down really well with Hornady One Shot lube making sure some got inside the neck, gave the size die a shot of lube and let it all dry for about 5 minutes. Then we just ran them through the 260 RCBS die and presto 260 rem cases. We found that we got best accuracy and velocity with H-4350 powder with 120 and 140 gr bullets. Rifle was one of the first Rem 700 SS with 24" barrel to come off the line. It was and still is a shooter.
  4. Kevin Thomas

    Kevin Thomas Well-Known Member

    Feb 16, 2009

    You'll find that a tapered exapnder ball, or better yet, and expander mandrel in a die specifically for this (Sinclair sells these, and they're pretty inexpensive) will do a much better, and easier job. Aside from that, it's all been covered; lube them and pass them through the die. You've now got 260 cases, ready to go.
  5. gr8whyt

    gr8whyt Well-Known Member

    Nov 26, 2010
    +1. I bought a Redding tapered expander ball. It works great. And it threads right onto the shaft of an RCBS decapping rod. They're about $14+s&h from Sinclair Intl.

    Tapered Sizing Buttons

    -- gr8whyt
  6. Clark

    Clark Well-Known Member

    Oct 19, 2006
    The 260 SAAMI drawing tolerances for the chamber neck are:
    a) .299 - .301" at the rear of the neck
    b) .298 - .300" at the front of the neck

    As best I can measure with pin gauges, my 260 [long chambered at Douglas] is:
    a) .299" at the rear of the neck
    b) .298" at the front of the neck

    I have used 308 brass, 243 brass, and 260 brass in my 260.
    My experiences are consistent, but not a complete verification of the synopsis I offer here of internet folklore mythology I have read about the 260:
    1) 7mm-08 brass is the best, good fit between chamber neck and ammo neck
    2) 260 brass is second best
    3) 243 brass is third best. It gets a donut formed at the base of the neck
    4) 308 brass is 4th best. Commercial brass will work. 10% of the time there will be a nasty pressure spike from a pinched bullet. These misfits can be sorted out, turned, or reamed.
    http://www.saami.org/PubResources/CC_Drawings/Rifle/260 Remington.pdf