Home Forums Reloading Big Game Rifles Necking down 7mm>6.5 brass introduces runout

I’m working on necking down new PPU 7x57 Mauser brass to 6.5x257 Roberts. Checking the new brass prior to resizing, every piece of brass has less than .003 runout, most are .002 or less. Looks like good brass.

When I neck down I’m lubing inside of case neck well, and die is set to just kiss the shell holder on the ram. After necking down most cases have .005-.008 runout. A few are .003-.004.

I tried a few with an o-ring under the locking ring, rotated a few 180*. Nothing really makes a difference.

I am using a new CH Tool and Die FL 6.5x257 die. I also have a Redding 7x57 FL bushing die. I can neck down the brass using my regular 6.5 bushings with no problem, but I only size at 60-70% of the neck doing this. I did not think the cartridge would chamber if the neck wasn’t fully downsized.

Will fire forming straighten the necks back to an acceptable runout? I did 20 cases and then stopped to get some opinions. Any thoughts or suggestions are appreciated.

How much is the expander ball of the 6.5 die having to open the necks on its way out?

Without the expander, sizing down to .245. Expander opens neck back to .260. So .015. I checked the runout without expanding the neck back up and it was .001.

That's about three times as much as I'd want to see. IMO, the neck section of that die is way too tight for the brass you're using.

I thought that also. I am going to give them a call tomorrow and see what they say.

I have an expander mandrel for a neck turning tool. I will try to expand the down sized case and see what happens. I could then neck turn, the resize with the Mauser bushing die. A lot of steps and probably need to anneal.

Thanks for the feedback.

I’m off today so I have been playing around with this a little more. I can size down without the expander to the .245 and runout is excellent. Then I can slowly push the case back through with the expander in place and get about .002-.004-5 runout depending on the case. I think it could possibly be better, but the expander is entering “backwards” with sizing portion hitting first.

Resizing from .245 with my neck turning mandrel produces the same. I would assume some of the runout is attributed to neck thickness differences.

I’m going to neck turn about 5 cases then send those through the bushing die and see what happens. I am also calling CH is a little bit.

After they are fired the first time they will be straight.

Agree

Thanks, I’ll finish up the twenty then fire form and see what happens with the cases. I’m waiting right now on a stock warranty fix, so it may be a few weeks.

They will straighten out when fire formed, but as tight as your die is at the neck, they may still show a lot of runout after the next resizing cycle.

I hope I can use the bushing die after the first firing. Maybe it will be better. I did call CH, but had to leave a message for a call back.

I was able to talk with CH Tool and Die this morning. He agrees that it seems the die is downsizing the brass too much— more than double what the standard is of about .007-.008. They want me to send the die in with a couple of pieces of new brass, sized brass w/o expander, and sized with expander.

He said they will take a look at the die verses print drawings and will figure out what is going on and replace the die if needed.

The more I thought about it over the weekend, it is almost down sizing the brass to below 257 Roberts specs, then expanding with 6.5 expander. He agreed that the numbers I gave him were not adding up.

We talked about fire forming would straighten the brass, but then when resized I’m back at square one.

Thanks for the suggestions and advice.

I've necked down 7-08 to 260 and 7mm Rem Mag to 264 WM. This would be with FL dies. Never good on runout. First fire forming always gets things straightened out.

Did you note how much excess sizing was being done?

Have your tried a Hornady Universal Neck Sizing Die in 6.5 mm?

I use one of those to neck down 308 and 7/08 brass to 260 Remington...brass has excellent accuracy...
don't have any thing to check out run out, but with not experiencing poor accuracy, I'm not worrying about it.
After being resized post shooting, that would straighten out any run out problems.

The Hornady neck sizing die originally cost me $20 or less. guess now they are $38.

https://www.grafs.com/retail/catalog/product/productId/5921

No, I ordered one as you had previously mentioned. Hopefully it will arrive first of next week.

Negative