I am considering building a 6.5 x 57R and I am wanting to neck down the 7 x 57 to a 6.5, will the case require neck reaming or turning? Or can I just resize the neck and load?

I used to have a rifle that I had rebarreled to 6.5 X 257 Roberts. Mostly I used .257 Roberts Brass but have used some 7 X 57 m/m Brass too. I never had to ream the neck or turn anything; I just full length resized and loaded.

Off the top of my head, I vaguely remember Ken Waters trying that in his Pet Loads chapter on the 6.5x57, and he had problems doing it. Maybe the shoulder angle on the 6.5x57 is different? Or located slightly differently?
Sorry, that's all my feeble old brain will spit out, and I'm not where I can grab my copy of Pet Loads and look it up for you.
Needless to say, consulting Ken Waters Pet Loads would be a wise idea.

I believe that is correct, IIRC the shoulder angle is different for the two cartridges. Which is why I would use the 7 x 57 and because I want a rim.

Don't know about the 7x57R, but I have a 6.5x257 AI that uses plain old 7x57 brass necked down to 6.5 with no problems. haven't had to inside ream. Have turned the outside of the necks though I'm not sure it was really necessary.

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Sounds good, I didn't realize it, but it seems S & B load 6.5 x 57 rimmed. I'll look for some info on it.

What kind of velocity are you getting with your 6.5 x 57? I am thinking of using 120's and 130's mostly.

Here's a side by side I pasted together from QuickLOAD's drawings. It looks like you have to neck down the 7×57R, trim, then blow the shoulder forward to go from 7 to 6.5. Whether you need to ream or not depends on your chamber's neck diameter. Most chamber reamers are little on the generous side for neck diameter unless you get a special one, so the extra brass could actually make it a better fit. Going by the difference in cross section area, If the 7×57R has a 0.014" thick neck, it would gain 0.001" in wall thickness if the brass all pressed inward instead of squirting up longer, which it will do. So I don't think that's going to leave you with much real thickness gain. Maybe half a thousandth or so. It is likely to be within tolerance for your chamber, but get a chamber cast or use a small hole gauge in the neck to be sure. Figure the chamber neck should be at least half a thousandth bigger at the end than the OD of the neck over a seated bullet. I would warn you about the dreaded donut if the 7×57R brass is used, but because the 6.5 neck is shorter than the 7 neck, any donut should end up in the shoulder, where it may be ignored.

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Thanks for the info! I was concerned about a donut!!!

I put together one - dummy round - from a 7 x 57, and I like the looks of it. It would be in a SS so there is no mag length issues.

Thanks again!

AJD - I'm using the Hornady 129 gr SST bullet with IMR4350 and a standard primer for a chronographed velocity of 2950 fps.

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Thanks! That is where I want to be with a 130. I shoot a lot of 260, and this seems like it is just a tad faster. I really like the 260 BTW, I just don't need another, currently (4). So I figured to try something different, but almost the same.