Resizing from 7x57 to 6mm causes bent neck

[CinciJeff]

Hi all,

This is my first post to the forum, though I've been reading it for a while.

I'm having a custom 6mm/244 AI built for me, and with the help of the gunsmith I've pulled together all (I think) the equipment I need to start resizing my brass. Since I have a few months before the gun is ready I wanted to get my feet wet and work on some of the fresh Norma 7x57 brass I purchased. (Note: I realize that 6mm Remington is the easiest to use for this application, but I wanted to work with the great Norma brass to create consistent loads)

So here's my problem - and it probably applies to any necking-down operation. Based on my smith's instructions, I'm taking the neck from 7mm to 6mm in two steps - first is with a Forster 6.5x284 FL die, and next is using a Redding 6mm/244 AI bushing die. The problem is that after coming out of the first die, the neck has three things wrong with it:
1) The lip is no longer pependicular to the case (ie, one side is higher than the other)
2) It's bent like a banana (related to #1 I'm sure)
3) The neck is no longer concentric to the case.

When I watch the lip of the case touch the inside of the first die (I removed the decapper and peered inside) I can barely see the thickness of the brass. So, that interference with the die is compressing the neck before it pops through. This can't be good.

I did take a couple test cases a few steps further, trimming and turning them, but the concentricity is still off, which will certainly screw things up once on of these tries to find its way into the chamber. I can see how fireforming would correct most of these issues, but it seems I should be able to do a better job off the bat.

Basically I'm looking for advice on what I might be doing wrong - or not doing at all - that I could change to make this work better for me. I've enclosed a picture (actually a combination of pictures) to show what my case looks like at various stages.

Thanks in advance for your help.

 

[243winxb]

My guess is you MAY need to trim the case first. The 7x57 is .011" longer than the 6mm rem. Sizing the neck smaller will make the case even longer. Drawings here .http://www.norma.cc/content.asp?Typ=59&Lang=2&DocumentID=269&Submeny=4&Rubrik=Calibers&Title=7x57%20Mauser The 6mm rem can be found here. http://www.stevespages.com/page8d.htm When the shoulder is blown out to AI then the case will get shorter. All a guess on my part.

 

[Steve Marshall]

When sizing in the 6.5x284 die the body of your brass is not supported. Since you are using virgin brass, I suggest you get some Imperial Sizing Wax from Graf and go straight to the 6MM die.

 

[243winxb]

The next problem you may have is the bushing sized brass might not chamber. This will be caused by the bushing die not sizing all the way to the shoulder. When sizing the neck down you may get a donut also. A standard FLRS die works better then a bushing. IMO, you just should have purchased 6mm rem brass and neck turned, then use a bushing die.

 

[NCsmitty]

Welcome to THR, CinciJeff.

IMO, you just should have purchased 6mm rem brass and neck turned, then use a bushing die.

Sensible advice from 243winxb.

When sizing in the 6.5x284 die the body of your brass is not supported.

If you get a set of regular 244/6mm dies, and size the 7mm brass, you should end up with much better results. Dropping the size 1MM in caliber is actually quite simple and the case support of the regular die will allow concentric necks.
No more banana neck, and you should be able to fireform successfully.
The initial case prep is essential, especially inside/outside chamfering.



NCsmitty

 

[longdayjake]

I would suggest going straight down to the 6mm and skip the 6.5 step as well. Someone suggested imperial sizing wax, but let me suggest that you go to lowes or home depot and buy a huge 20oz bottle of wire pulling lube. I use it to size 6.5 grendel from 7.62x39 and I have yet to destroy a case. It is a wax lube as well, but in a liquid form.

 

[ants]

You're getting some good words from the other guys. No need to repeat.

But have you taken this back to your 'Smith' and shown him your brass product?

As a humble little reloader, I don't think I would employ a bushing die to resize 7mm to 6mm. I've never done that in 40 years. A neck bushing is excellent for its intended job, but this isn't it.

You should have a kind word with your smith, because he may know something that we don't know. Or maybe not...

 

[CinciJeff]

Thanks for the suggestions - and the welcome!

Ants: actually I have sent him the same picture I posted in the first message, and am awaiting a response. I feel like I've been bombarding him with questions lately and I thought I could benefit from the insight of this forum and lighten the burden on him a bit. If he was closer I'd talk to him personally (and he could show me the process) but he's several hundred miles away so it makes logistics a bit difficult.

6mm Remington
My gunsmith basically gave me two options for brass. Fireform 6mm Rem and I'm good to go, or for the greatest accuracy (via brass consistency) jump though many more hoops and work with the Norma 7x57. Since I'm not getting the rifle until this winter, I figured I'd take the extra time to learn how to resize the 7x57. If that didn't work, I could always default to the 6mm Rem. I reasoned that after spending a lot of $$ for a super-accurate gun, I should take the next logical step and try to use the most accurate ammo. Besides that, I'm always up for a nice abusive challenge .

Straight to a 6mm die
I didn't mention it in the first message, but I have been using the Imperial Sizing Wax - so I'm covered in the lube department. After reading the messages I went to my bench and tried a 7x57 case right into the Redding 6mm/244 Imp. die. It didn't go well. (see photo)


I sketched out a scale diagram of what's going on in the die, and it just doesn't seem like the ideal setup to shrink that diameter. There's just too much interference and the angle isn't shallow enough to gently draw in the material. To those who suggested this method, am I missing something?
'

Ideally, the case would be fully supported (radially) and the lead-in to the smaller diameter would be shallow enough to both center and compress the O.D. of the neck. Maybe some sort of collet resizer would work?

Ants, ultimately you have it right. Somehow he's making it work, and I'll figure it out eventually. I tend to learn best by gathering a lot of data and sorting it out. Once I get it figured out I like to repeat it back, so look for another post with the details of what I learned.

 

[counterclockwise]

I've been going from .308 down to 7mm-08. I like the RCBS Case Lube 2 better than Imperial. Imperial is much more viscous than the RCBS, but the latter seems to reduce sizing friction more. I have to stop at least once, maybe twice and trim, because the neck gets longer when it is reduced. Relube every chance you get, particularly the neck because the sizing forces are high. Keep the expander stems out of action during the neck sizing. Just take them out. The neck is going to get thicker, and the combination of increased neck material thickness and regular expander stems will lock up your press.
Plan on reaming and peeling the neck after downsizing to restore proper thickness and get rid of the famous "dougnut" (internal bump at junction of shoulder and neck). After that, reinstall the expander stem and finish full sizing.