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Necking down .308 to .260

Teamblue
I just got a new .260 Remington rifle and want to reload for it.

I have a whole bunch of Black Hills and Federal GM .308 brass.

What is the best process to follow to neck it down to .260Rem??

Both cases have 20 degree shoulders. Thanks!!



"Blessed be the Lord, my rock, who trains my hands for war" Psalm 144

Nemo Me Impune Lacessit
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Comments

5 comments

Date Votes
  • ern98
    If you have any dies in a 7mm I'd probably start there and just size the neck from 30 to 7mm and then 7mm to 6.5mm with the full length size to get what I'd hope would be a ready to go 260rem. Also I'd want to trim the case length between steps as the brass will stretch each time. Assuming that the case will chamber with out anymore rework, I'd probably then plan on a very light load for the first range run. This wouldn't quite be fire forming but it would still be a good idea.

    Do you load using a RCBS case master or the like? The case master is a set of V block with a dial indicator to measure the run out. Run out is how out of allignment with the axis the brass is. Small amounts like .001 is ok but like .004 is too much and I find out whats wrong n fix it. Using a case master will be a good form of quality control on your converted brass. Because if the brass isn't straight then you can't get the bullets to go in straight, and you can't expect good accuracy if everything is out of line from the get go.
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  • nononsense
    Teamblue,

    I think that there are a couple of other things to add here.

    Be sure to use some form of lubrication whenever you are converting or sizing brass cases. There is nothing worse than spending the time to convert some pieces and stick a case in a die. It is a pain to get it out of the die. I use Imperial Sizing Wax.

    My preference is to neck up when possible, which it isn't in your situation since you have quality .308 brass to work with. Be aware that when necking down, brass in the neck area will get thicker. Two things can happen; you will probably have to outside neck turn the case to get the O.D. of the neck to be the correct size of a loaded cartridge. Standard .260 Rem. chambers have a neck diameter of 0.298" and a case neck size of 0.294" with a bullet seated. That leaves a clearance of 0.002" per side for expansion and release of the bullet. After firing, it is possible that a doughnut will form at the junction of the neck and shoulder on the inside of the case. This will have to cut away with an inside reamer. Be sure to check for this doughnut after each firing.

    Remember to chamfer the inside/outside of the neck after trimming to eliminate the burrs. Check the fit of every case before loading. Create a dummy round using the bullet or bullets of choice in order to aid in setting up your dies.

    If parts of this don't make sense, find someone local to give you a hand to get started.

    Best of luck.
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  • mrbruce
    No problem, but using Redding bushing dies in steps will make it a easy thing to do.
    K&M services in Pa. makes a neat little doughnut remover reamer that you will probably need because the extra brass from the 308 has to go somewhere, and it goes in the necks.
    I wouldn't mix the brass either, nor would I use it if it has been fired before in another rifle.

    Gun control is hitting what your aiming at.
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  • gotstolefrom
    Hey, I like to reload as much as the next guy.
    (Well, after you , maybe not)

    I just would not want to do a resize as tedious at this could be.
    I'd have to go for new brass/ammo.

    The head stamp on resize is a potential problem. Though I have seen a guy take the 'electric pencil' to them.

    ENJOY
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  • He Dog
    TeamBlue, Der Gebirgsjager rechambered a rifle for me to .260 and did some loading to test it out. No doubt if you drop him an e-mail, he will offer lots of good advise.
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