Necking up 6.5 brass to 7mm, correct process

[DennisH]

As the title states, what is the correct way to neck up 6.5 brass to 7mm.

Some state use an expander mandrel first, then use the FL sizing die to finish off the brass.

I am taking 6.5x284 brass and necking up to use in a 284 Winchester.

Thanks for your opinions, Dennis

 

[spclark]

Should be just the mandrel that's necessary. If the brass is new you ought to be able to open it without annealing first. If used I'd anneal 'em to avoid splits and non-uniform neck tension.

Before you run a bunch then load 'em, check how the first ones fit your chamber. I doubt you'll need to size the bodies but you never know 'till you try! If your bolt will close on a necked-up case you ought to be good to go to the next step.

 

[fguffey]

Yes, use the full length sizer die, lube the inside of the neck and outside the case, avoid lubing the shoulder and outside of the neck, measure before and after, first measure the case length, the case should shorten when necked up, when necked up the neck shortens, when necked down the case neck lengthens, then there is the other school of thought, goes something like the neck thickens and or thins when necked up and or down, I will leave that to be sorted out by those that make that stuff up.

As has been discussed, in the perfect world new cases are used when forming, next best case to use is the once fired case, then there are those that claim all that is required to start over is ‘full length size’ after firing to form then neck size after firing 5 times, and I find that impossible, to complicate their methods and techniques they refer to it as ‘bumping’.

F. Guffey

 

[spclark]

I forgot most folks probably use the expander ball sold with most F/L case dies.

I don't, preferring instead to use neck bushings in the case dies, or an expander mandrel separately.

Obviously you have to use something to open the necks up, but whether you need to F/L size also is up to you. If necked-up cases fit your chamber & allow your bolt to close with no unusual effort, I'd say you've done enough.

Oh: necking up (expanding) will thin case necks - the brass stretches. Neckind down does the opposite & often requires reaming (inside) and/or neck turning (outside) as otherwise necks can be too thick to safely use in many chambers... if they'll even fit at all after loading a bullet.

Safest bet? Check chambering fit after every step in the process. Avoid surprises.

 

[fguffey]

“Oh: necking up (expanding) will thin case necks - the brass stretches. Necking down does the opposite & often requires reaming (inside) and/or neck turning (outside) as otherwise necks can be too thick to safely use in many chambers... if they'll even fit at all after loading a bullet”

For those that do not measure before and after the neck thins when necked up, for those that measure the length of the case before and after have a problem explaining the case getting shorter when necked up and longer when necked down.

F. Guffey

 

[habu]

go to sinclair and get a 7mm TAPERED EXPANDER BUTTON - HORNADY

after running about 18-20 cases through it, [fired] it's going to get 'sticky'. DONOT SCRATCH THE BUTTON trying to get carbon off!! acetone doesn't work - USE A STANDARD INK EREASER!!

takes carbon off, no scratches.

did 500- 6.5x284 NORMA cases in about an hour& half.

habu

 

[dennisinaz]

I use a K&M expander mandrel. My second choice is a tapered (Redding special button) or eliptical (Hornady) die. I strongly recommend against using a standard RCBS or Redding expander ball for this.

Hornady makes a die body just for this. I think they are about $20.

 

[DennisH]

I strongly recommend against using a standard RCBS or Redding expander ball for this.

I just bought a RCBS 284 neck expander die!

Now you have me curious on the above statement! The RCBS "won't" get the job done?

 

[dennisinaz]

I am not familiar with an RCBS neck expander die. If it is an RCBS neck sizing die then, no, it won't get the job done. You will probably collapse a few necks trying to get that cylinder to enter then undersized neck. Redding makes a tapered button just for doing this. The standard Hornady button is elliptical in profile and works quite when for this too. You want the button to gradually force the walls of the neck out.

I have made hundreds of 260 Remington brass out of 243 Lapua before they came out with their own 260 brass. I tried every method you can thing of and a few you can't! I got the least runnout with the K&M expander mandrel and die. Once you fire the brass it doesn't matter but my fireforming loads (full power) were more accurate using the K&M tool than anything else. It is a very inexpensive tool.

As far as neck sizing dies go, a cheap neck sizing die will create more runnout in a case neck than anything else you can possibly do to it. A very good bushing die is another story but a standard neck die is bad news.

 

[DennisH]

@ dennisinaz, no the die I am refering to is part number 39815, NECK EXPANDER DIE .284, which is strickly made to neck up brass. It has an expander mandrel and serves no other purpose other than necking up your smaller brass. I will then run it through my FL bushing die, clean, and start the loading process.

39815, RCBS Neck Expander Dies are specifically designed to flare the inside dimension of the case neck to slightly greater than the bullet diameter ensuring perfect alignment of the bullet during seating.

My understanding is the RCBS expander Die has an Expander Mandrel. If this is incorrect, please let me know!

The normal FL bushing die uses a ball expander.

I will check out the Hornady die to make sure I am on the right track! Lapua brass is too expensive to mess up.

The RCBS may not be the item I need to neck up my brass, please advise.

 

[rain164845]

I went from .243 to 7-08 with the hornady 7mm expander and I ended up with horrible runout and uneven case mouths. I used redding lube inside the necks and a faint coat outside. I hope 6.5 to 7mm isn't as bad.

 

[DennisH]

A very good bushing die is another story but a standard neck die is bad news

I have a Forester FL neck bushing die for my 284. As per your comment on a good bushing die, tell me the correct "necking up 6.5x284 brass to 284/7mm.

As stated, Lapua brass isn't cheap and I want to do it wright for the start!