Alternative to inside neck turning

[Straightshooter1]

Inside neck turning has always sounded like a good thing to do, but apparently one needs some very special and expensive equipment to do it right, and . . . there's the question of whether the effort and expense is worth the improvement it might provide.

I find neck turning the outside really helps with improving the tuning of the cartridge and so I do that on all my brass after fire forming it. But, I've often struggled with thoughts on how the fire forming tends to move any neck wall thickness variations from the outside to the inside (to some degree or another), which seem to kinda defeat the effort to get a uniform thickness so that one has even neck tension all round the neck.

When I used a Lee Collet Die, I took measurement before and after and found that I'd gain .002 - .004 in case size. So, the collet is squeezing the neck and like would happen if it were clay, the brass squeezes the brass outward as it's being pressed against the mandrel. As I thought about what is happening here, it occurred to me that the process was not only squeezing the brass making the neck longer, it was also squeezing the brass to where the wall thickness was being evened out over the entire neck (much like squeezing clay around a pipe, leaving a perfect impression of that pipe). Though, unlike clay, brass will have some spring back (if it's not overly annealed, of course).

So, in order to see if this was actually happening, I took some brass that had significant differences in neck wall thickness, measuring them with a tube micrometer before and after the use of the Lee Collet Die. Sure enough, after running them through the die, the variation in wall thickness was reduced. And then, after turning the outside of the necks, I found a variance running from .0002 - .0004 in thickness. This variance was way less than what I had before I turned them, indicating that the Lee Collet Die had moved most of variance to the outside.

Having gotten these results as led me to use the collet die all time time only before doing any neck turning. And I'd say it's helped a lot in getting uniform neck tension.

Many times I searched the net, including this web sight, to see if anyone else has been doing this and I haven't see nor heard anything about it. How about anybody else here? Has anyone ever heard of this?

 

[mikecr]

I took some brass that had significant differences in neck wall thickness, measuring them with a tube micrometer before and after the use of the Lee Collet Die. Sure enough, after running them through the die, the variation in wall thickness was reduced. And then, after turning the outside of the necks, I found a variance running from .0002 - .0004 in thickness. This variance was way less than what I had before I turned them,

This supports your theory that the collets are rolling thick into thin against the mandrel. Makes sense.

indicating that the Lee Collet Die had moved most of variance to the outside.

Here, you missed the meaning of your evidence. The collet die did not push thickness variance outward (collets prevent that), but into thin areas and elongating necks. Basically squishing brass toward the only directions it can.

Keep in mind the reloading basics that would have you always expand necks before seating bullets. I call this pre-seating expansion. This moves a high percentage of thickness variance to the outside, where it doesn't matter a bit.
Neck turning won't ever remove all thickness variance, but enough to make ammo that is straight enough.

 

[Straightshooter1]

Here, you missed the meaning of your evidence. The collet die did not push thickness variance outward (collets prevent that), but into thin areas and elongating necks. Basically squishing brass toward the only directions it can.

OK, I agree . . . it's not actually pushing the thick portions outward. But it's pushing that brass around withing the neck, and as you say, it's going in the only direction(s) it can as it "fills in the high/low voids" to some extent (to think of it in another way).

Keep in mind the reloading basics that would have you always expand necks before seating bullets. I call this pre-seating expansion. This moves a high percentage of thickness variance to the outside, where it doesn't matter a bit.
Neck turning won't ever remove all thickness variance, but enough to make ammo that is straight enough.

Yup, I agree again. That's exactly what I do as a matter of routine. And I'd point out that when one is getting ready to turn the outside of the necks, an expansion mandrel is run through the neck to make it the proper size for the turning mandrel . . .

. . . and the resulting diameter might be just the right tension???

 

[JSH]

So in effect your saying, it is moving thick brass to thin side?
I gotta say no. If and that is a big if, it is moving your brass is dead soft or you are working the holy crap out of that die.

If it is moving, explain why fire forming would not swage it to the “thin” side in ultra seconds when fired......or smear it forward down the chamber.

Brass is soft, but it isn’t that soft.

Not an argument just a question for discussion

 

[varget204]

K & M sells a neck turning mandrel that is also a 4 flute inside neck reamer,kill 2 birds w/ one stone

 

[JSH]

Neck reaming makes it round. It may not be true center. If there is enough material both may or may not be better.
The cases I reamed long ago were way out when done.
The reaming will remove material on the complete inside surface.
Outside turning will only remove the high spots.

 

[Dusty Stevens]

K & M sells a neck turning mandrel that is also a 4 flute inside neck reamer,kill 2 birds w/ one stone

It also threads the inside of the neck with a nice acme thread if you like that

 

[Dusty Stevens]

I guess the main takeaway here is put the collet die in the drawer with the other dies that dont work, get a good neck turning setup and a good fl bushing die- no more weird issues popping up here every few days between collet dies and neck sizing.

 

[Straightshooter1]

So in effect your saying, it is moving thick brass to thin side?

Essentially, yes.

I gotta say no. If and that is a big if, it is moving your brass is dead soft or you are working the holy crap out of that die

Just how much it can move depends on just how soft is might be. Yeah, if it's dead soft, it's going to move pretty easy. But even if it's not "dead soft", it's still going to move and will have some spring back depending how just how soft or hard it is.

If it is moving, explain why fire forming would not swage it to the “thin” side in ultra seconds when fired......or smear it forward down the chamber.

Fire forming doesn't do it because the pressure is equal across the entire inside surface. The squeezing against something like a hard mandrel your putting pressure on the high parts before there's any pressure on the lower parts.

There's good reason why necks and shoulders are not over annealed as they would pretty much do what you say in "smearing" forward and without spring back would get stuck.

Brass is soft, but it isn’t that soft.

But, maybe softer than you think . . . particularly the annealed parts.

Not an argument just a question for discussion

Not a problem. I do appreciate the thoughts and hope for such challenges to help find the flaws in my thinking. As in any science, peer review is an important aspect for finding the truth as scientific theory is always open to question.

After 30 years of participating in various chat rooms and forums, I've developed a pretty thick skin anyway.

 

[Willie]

The K&M tool is more for cutting out donuts, than for inside reaming. As Dusty said, you're not gonna like the inside of your necks, when reamed.

The tried and true method works best, expand and turn the outside. If done properly, it should give you less than .0005". JMO

 

[1shot]

In regards to dealing with donuts, I feel you have to legitimate options. 1. Push the donut to the outside with a mandrel big enough to do it right, and then use a turning mandrel properly sized to support the neck/shoulder junction when you turn them.
2. After you cut your chamber on a fresh bbl. go in with a throating reamer and remove just enough material so that the trailing edge of the bearing surface is just above the donut, then do ever worry about it again.
I hope this helps,

Lloyd

 

[NorCalMikie]

Why not just use a mandrel to push the donut to the outside of the neck and turn it off?
Or, better yet, just seat the bullet above the inside donut? Keeping it as simple as needed. My bet is most have a long enough chamber throats to use bullets that won't touch the donut area.

 

[varget204]

It also threads the inside of the neck with a nice acme thread if you like that

One only has to go slow cuts even,have to be smart enough to use it.

 

[mauser284]

I think it depends on the cartridge, the load and the application. I spend very little attention to neck and neck tension on my hunting ammo because it just does not matter in 90% of the situations especialy with a factory rifle. In fact if it is a hard recoiling cartridge or a straight walled lever gun cartridge I am prob. going to crimp it on purpose. On the other hand I would not dream of showing up to a competition with out every detail of my brass being accounted for to produce the finest accuracy and consistency I can produce. Every situation is not the same and does require the same attention to detail. I am sure their is some guy with more money than brains that is having his 'smith build a Mas 49 to the same levels of precision as his BR rifle. So painting with too broad a brush is silly at times. the 5 "W's" matters more than is reflected on this forum a times!

 

[L W P]

K & M sells a neck turning mandrel that is also a 4 flute inside neck reamer,kill 2 birds w/ one stone

But how can you be certain that the brass in the collet is centered exactly with the inside reamer every time? As far as using the Wilson inside reamer.

 

[Dusty Stevens]

But how can you be certain that the brass in the collet is centered exactly with the inside reamer every time? As far as using the Wilson inside reamer.

The k&m is handheld and runs out with the brass