Neck sizing theory and process

[gremlin]

Rather than reading through countless threads (which I have) to get a specific answer, I was hoping to throw this post out there. If this has been addressed before, please point me to the discussion.
I'm trying to get my head around neck sizing. I do understand neck tension and proper use of the right neck bushing. What I don't understand is the physics of using a neck bushing in combination with an ID ball sizer on the decapping rod. As I understand it, the ID ball sizer will enter the neck and effectively size it to the bullet size on the up stroke and then the neck will enter the bushing, downsizing the neck for proper tension. But then on the downstroke, the neck will again have the ID ball sizer pass through it making the neck bigger. Am I missing something here? Is this the proper procedure? I purchased the Redding competition 3 die set for .338 Lapua. I have been loading pistol rounds for several years and know the necks can become "dented" in. For this reason, I also purchased the decapping rod with the ID ball sizer. Is this process going to put undue stress on the neck over time and weaken it? Is it the right way to do this? Any light you can shed on this will be greatly appreciated. Any text you can point me to would also be greatly appreciated. Thank you for you time and wisdom.

 

[steve123]

Most guys take the ball sizer out and just use the decapper with the proper sized bushing.

I try not to use ball sizers if possible because they stretch the neck more and you end up having to trim more often.

In certain situations I've run across with non Bushing FL sizers I've polished down the ball sizer to a smaller diameter to give me less neck tension, ride through the case easier and stretch the neck less.

 

[George63]

you certainly are not understanding the mechanics: with fired brass, the ball should not touch the neck on the way up with any die

if you cannot understand why, you definitely need more reading/ info/ experience - not less

read some books - get a mentor -

REPEATED MANY TIMES:
forums are not the place for beginner loading info

 

[gremlin]

I believe my question stated that I AM trying to understand the mechanics. It seems that what you are saying is that I should be an expert before asking questions. I have reloaded THOUSANDS of pistol rounds. I could have easily purchased a progressive reloader, followed the instructions, and reloaded thousands of rifle rounds successfully, without understanding the theory behind it. I am not a "button pusher", I like to know whats going on behind the "button". If you want to chastise me for not understanding the theory, and then not answer the question, why did you even post a reply?

 

[FN in MT]

Most guys take the ball sizer out and just use the decapper with the proper sized bushing.

I try not to use ball sizers if possible because they stretch the neck more and you end up having to trim more often.

In certain situations I've run across with non Bushing FL sizers I've polished down the ball sizer to a smaller diameter to give me less neck tension, ride through the case easier and stretch the neck less.

THIS Says it all.

I'm a long time reloader....... a solid 45 years with lots of shotshells and pistol rds down the tubes. But my first foray into precision rifle started this past summer. It IS a different situation. I had the same question when I bought my first set of bushing dies. So your not alone.

WHY they also include a smaller spud that simply holds the decapping pin in place when you remove the neck expander plug.

FNin MT

 

[Clark]

The SAAMI specs on chambers and cartridges are wide sloppy tolerances with no over lap.

This makes for lousy chambers and lousy dies. Together they torture brass and reduce accuracy.

Using the 308 as example:
The SAAMI spec on the chamber neck is from .3462" + 0.0020"
The SAAMI spec on the cartridge neck is from .3435" - 0.0080"

That would make one think that the clearance between cartridge and chamber would then be randomly somewhere between 0.0027" and 0.0127".

But what really happens is the chambers are made as close to the minimum and the ammo is made close to the minimum, so the clearance is a narrow Gaussian distribution centered near 0.0107".

A typical .308 full length sizing die with have in a neck inside diameter of 0.328".
So the die squeezes the case neck down to .328" and it springs back to .329".
The case is then fired in a .347" chamber and springs back to .346".
The die squeezes the case neck down to .328" and it springs back to .329".
The case is then fired in a .347" chamber and springs back to .346".

This happens a few times at .346 - .329" = .017" of plastic deformation and then something happens, the necks get work hardened.

C26000 brass is tempered to H06 hardness at the case head [65,300 psi yield] but the necks are annealed.
With work hardening the necks start to spring back further and stand some chance of splitting.

What can you do?
Pay extra for a no turn neck chamber reamer at 0.335".... not sloppy SAAMI.
Pay extra for a FL die honed out to 0.330".
Now instead of .017" of plastic deformation per shooting and resizing cycle, you have .003".
Or if you want to turn necks like benchrest shooters, you can get it down to nearly NO plastic deformation.

As soon as the crazy amount of resizing go away, the expander ball may pass through the neck without causing any more plastic deformation. But who needs the extra friction?
Expander balls belong in the junk box.

 

[milo 2.0]

In your die box, in a sleeve, there should have been a black decapping pin retainer, looks like expander ball, but smaller in diameter, use this and your neck diameter will equal your bushing size.

Clark is spot on, as far as a non bushing die goes, both FL and neck dies, the dies crunches the neck way too far down, the expander ball brings it back to dimensions.

 

[918v]

Gremlin:

A standard sizing die accepts a fired case on the upstroke. The expander ball does not touch the ID of the neck at this point. The neck then gets swaged down to an ID way way smaller than it needs to be, depending on case wall thickness. That's too tight for a .308" projectile. So the expander ball opens up the ID of the neck on the down stroke.

What a bushing does is size the neck less so the expander ball does not have to work as hard. Because the neck is worked less, it lasts longer. But one bushing does not work for all makes of brass. Military brass requires a looser bushing due to having thick case walls. Win commercial brass requires a tight bushing due to having thin case walls. Lapua requires something inbetween.

 

[bruddah]

Gremlin:

A standard sizing die accepts a fired case on the upstroke. The expander ball does not touch the ID of the neck at this point. The neck then gets swaged down to an ID way way smaller than it needs to be, depending on case wall thickness. That's too tight for a .308" projectile. So the expander ball opens up the ID of the neck on the down stroke.

What a bushing does is size the neck less so the expander ball does not have to work as hard. Because the neck is worked less, it lasts longer. But one bushing does not work for all makes of brass. Military brass requires a looser bushing due to having thick case walls. Win commercial brass requires a tight bushing due to having thin case walls. Lapua requires something inbetween.

I like this explanation.

 

[earthquake]

In your die box, in a sleeve, there should have been a black decapping pin retainer, looks like expander ball, but smaller in diameter, use this and your neck diameter will equal your bushing size.

Ah, so that's what that is! Thanks and thanks to the OP...i was in the same boat before reading this thread.

 

[Clark]

The best brand decapping die is Lee.

Can't say that about too many things.

 

[gremlin]

As I stated before, I bought the ball sizer decapping rod for one reason, to size the ID of cases that the neck was slightly out of round, dented or maybe slightly flat on one side. I guess some of you skipped over that part. The heart of my question was, why expand the ID AFTER downsizing the OD of the neck. I understand now. A couple great answers made me "see the light". To add to the answers, I posed the same question to Redding, the people that made my dies. This is their answer . . .

--------------------------------------------------------------------------------------------------------------------------------
Parker Freshwater <[email protected]>


Hello,

Excellent question and a common one. It shows you are thinking!

Keep in mind several things:

Brass is mealable, and has a natural springiness, and it is NOT generally exactly the same thickness from one cartridge to the next, even in its own body.

With that in mind, lets talk neck sizing with and without an expander ball.

First, let it be known that one can, and some do, remove the expander ball. Some handloaders feel it helps. Our personal experience is that we see no positive effect removing the ball.

The expander ball is actually usually a bit smaller than bullet diameter. (I just mic'ed my 308 WIN die for reference as I wrote this) Mine is .306, as best I can measure, and sometimes the who in measuring is more important than the how!

You are correct that the ball will pass thru the neck going up and down, as the case is neck sized. We find that concentricity is not effected negatively by the expander ball, and in fact is positively effected in many cases. as far as "wear", we do not see much over-stress from this practice. By using a bushing, the handloader can better match the amount of sizing necessary for his brass and chamber, rather than using a standard one size does it all neck die. We find that "over-sizing" far overworks brass, and effects it much more than the use of an expander ball.

Opinions regarding this practice vary, and you may search multiple internet forums where discussion on this have been tossed about.

I hope this helps
--------------------------------------------------------------------------------------------



Thanks to all who responded positively

 

[earthquake]

In your die box, in a sleeve, there should have been a black decapping pin retainer, looks like expander ball, but smaller in diameter, use this and your neck diameter will equal your bushing size.

Clark is spot on, as far as a non bushing die goes, both FL and neck dies, the dies crunches the neck way too far down, the expander ball brings it back to dimensions.

This? Replace the silver one on my die, with the little black one? A quick aside, would it make sense or is it normal practice to use the black one to remove spent primers and not resize at this point (no neck bushing inserted), then tumble the brass, then run them through the die again to resize with the bushings, expander ball and bumping the shoulder and all that? Sorry for the hijack, but I'm still learning and the more I stumble upon threads like this, the more I learn.

 

[gremlin]

I'm with you on this. I bought a low-end Lee single stage press and a Sinclair decapping die to remove primers in a seperate process. The process of decapping is a very dirty process and I want to keep that dirt away from my expensive press and dies. I was going to buy a seperate hand decapper tool but the set-up I have now was about the same cost and I think a little sturdier. So ya, I decap then tumble.

 

[Clark]

The process of decapping is a very dirty process and I want to keep that dirt away from my expensive press and dies.

I have my servants decap my dirty brass. I can't stand to watch.

 

[milo 2.0]

This? Replace the silver one on my die, with the little black one? A quick aside, would it make sense or is it normal practice to use the black one to remove spent primers and not resize at this point (no neck bushing inserted), then tumble the brass, then run them through the die again to resize with the bushings, expander ball and bumping the shoulder and all that? Sorry for the hijack, but I'm still learning and the more I stumble upon threads like this, the more I learn.

I guess it depends on whether it's a neck, or fl die, I can't see lubing twice with fl??? If I'm neck sizing, I tumble, size, prep=chamfer and primer pocket clean, then prime and load.
For FL, I tumble, lube, size, re-tumble, prep+ primer pockets, have a awl to poke pin holes clean, chamfer, prime and load.
Every one has a diff routine, no one is right.

But yes, loose the silver expander, replace it with black one, for dinged necks, you may have to put it back on periodically to straighten them out, if you don't have a expander die, it's a die for neck turning, but come in handy as hell for this. FUN hah?

 

[milo 2.0]

I have my servants decap my dirty brass. I can't stand to watch.

Good one!

 

[milo 2.0]

In certain situations I've run across with non Bushing FL sizers I've polished down the ball sizer to a smaller diameter to give me less neck tension, ride through the case easier and stretch the neck less.

I'm not sure what neck tension Steve is referring to here, tension while case is in the die, or desired neck tension???
But if you polish the expander ball down in diameter, you'll have considerable more neck tension when seating a bullet. I'm not questioning his motive, but in reg dies, the ball is there for a reason.

I guess I should elaborate more. In my 7 saums, I run a .312 bushing in Redding dies. I have a RCBS X-die also, out of the x-die, necks measure .312. if I remove the stem altogether and size, my necks measure .308. Way too much neck tension on thick brass like a saum. I tried the polishing thing also, just had a dilapidated pile of shit, out of round, for 14.00 bucks, I got a new one!

 

[gremlin]

I had minions, but my pool cleaner ran off with my maid, so now I'm stuck doing everything . . .

 

[earthquake]

I guess it depends on whether it's a neck, or fl die, I can't see lubing twice with fl???

It's a fl die, Redding. I have three different sized neck bushings now, .292, .293 and .294". Haven't gotten to that step yet...still reading, and doing lots of research before jumping in. So is a decapping die something different than a sizing die? I should run cases through a decapping die to remove the primers, tumble, then size them with my sizing die, then trim?

I guess I'm confused on whether a decapping and sizing die are different items? Doesn't a sizing die "de-cap" too? Heck, maybe I'm not clear on what decapping is...isn't that the removal of the spent primer?

 

[milo 2.0]

I guess I'm confused on whether a decapping and sizing die are different items? Doesn't a sizing die "de-cap" too? Heck, maybe I'm not clear on what decapping is...isn't that the removal of the spent primer?

Most die making companies offer a universal decap die, it'll work for most cases, where the cutoff is, I don't know. I know RCBS wont do a cheytac! A sizing die decaps.

Like I said before, you'll have to develop a routine. I suppose if you're ss tumbling, a decap die will come in handy. Corn or walnut media wont do much on a primer pocket, but there's other tools that can.

 

[earthquake]

OK, thanks. I haven't gotten around to getting a case tumbler yet. Money wise, I'll most likely end up with a corn/walnut type.

 

[agbm]

Check this out, I think it will help. http://www.snipershide.com/shooting...8-hand-loading-precision-rifle-pic-heavy.html