On Neck Turning?

[Grump]

When I adjusted the durned thing, it was shaving about half the diameter by about mid-neck, increasing to up to full diameter the last .10 or less in front of the shoulder.

That's at about .015 thick, probably a bit less since I'm not using knife-edge calipers.

Different make of brass, it's now hitting pretty much nothing on most of them the first .10 back from the mouth, about half diameter the half of the neck closest to the shoulder, and some are getting nothing until the last .05 right next to the shoulder.

I'm reluctant to go thinner because these turned, sized and loaded necks are showing .01 smaller than the fired case necks.

Is this enough to make a difference or should I make them thinner? The targets aren't seeing much difference yet.

Thanks!

 

[prosise]

Re: On Neck Turning?

Sure wanting to bite my tounge on this one,

Sorry brother but I am not quite following you on the explanation. Couple of additional things might help.

Is this a standard chamber or tight neck chamber?
New or used brass?
If new, did you OAL trim Then expand to uniform the neck?
If used, Are the cases OAL trimmed?
Specific reason your neck turning?
what type of trimmer are you using?

THanks

Prosise

 

[flashhole]

Re: On Neck Turning?

I read your post 3 times and I agree, a bit more info is needed. Can you post a pic? Some of the brass may be too thin to trim at all, especially if you want .015" thickness.

 

[k2peaker]

Re: On Neck Turning?

Don't know if this is what you're asking but I turn pretty much all my necks (.260 most of it from .243 Lapua or Win).
I set my neck turning depth to achieve slightly thinner necks than .015". I end up in the .013-.014" range. This seems to work for me in terms of getting uniform necks, chamber well, etc.
In terms of how much brass is shaved off to get there? It depends on the brass mostly by manufacturer. With Win .243 its a far amount from the mouth to the shoulder. With Lapua it's less until I get to the shoulder area where a decent ribbon is produced.

 

[427Cobra]

Re: On Neck Turning?

Grump do you have tight neck chamber that requires you NT every piece of brass in order for them to chamber, if not your wasting your time by turning the entire neck, just hit the high spots, .013 -.014 is good enough, if your turning them farther than that you'll increase the work hardening of the brass because it will have to expand further and you'll have to size it down further, thus increasing the need for annealing, last but not least are you a consistent 1/2 inch shooter at 200 yards, I'm not, and I bet most here are not so really is NT required?

 

[Country]

Re: On Neck Turning?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 427Cobra</div><div class="ubbcode-body">Grump do you have tight neck chamber that requires you NT every piece of brass in order for them to chamber, if not your wasting your time by turning the entire neck, just hit the high spots, .013 -.014 is good enough, if your turning them farther than that you'll increase the work hardening of the brass because it will have to expand further and you'll have to size it down further, thus increasing the need for annealing, last but not least are you a consistent 1/2 inch shooter at 200 yards, I'm not, and I bet most here are not so really is NT required? </div></div>
For a factory chamber what I do is just clean up about 75% of the diameter , make sure you run the cutter down onto the start of the shoulder and just take a very slight cut on the shoulder. This prevents leaving a ridge at the shoulder junction which becomes a donut on firing.
Then to reduce work hardening and to regain lost diameter of the neck in the chamber I partial size the lenght of the neck leaving a short unsized section above the shoulder . Kinda like a slight second shoulder. This is never ever sized again unless you decide to re-turn the necks at some stage. keep it fairly short and if it makes chambering harder even when you know the case is body sized right then shorten it more. This second shoulder acts somewhat like a tight neck chamber giving better centering and the neck turning gives more even neck tensions and better sizing operations. I discovered this technique for a bolt action many years ago after I invented my first body die by cutting the tops off standard full length sizing dies and grinding the neck diameter out. It's worked for me for the last 35 years so I think I have tested it well enough. Not really suitable for an auto though. If usinga Lee collet die to size then yoy can shorten the size lenght by placing a machined washer of the correct thickness over the case and ontop off the shell holder during sizing , it's a bit fiddly but you get used to it. .

 

[Country]

Re: On Neck Turning?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Grump</div><div class="ubbcode-body">When I adjusted the durned thing, it was shaving about half the diameter by about mid-neck, increasing to up to full diameter the last .10 or less in front of the shoulder.

That's at about .015 thick, probably a bit less since I'm not using knife-edge calipers.

Different make of brass, it's now hitting pretty much nothing on most of them the first .10 back from the mouth, about half diameter the half of the neck closest to the shoulder, and some are getting nothing until the last .05 right next to the shoulder.

I'm reluctant to go thinner because these turned, sized and loaded necks are showing .01 smaller than the fired case necks.


Is this enough to make a difference or should I make them thinner? The targets aren't seeing much difference yet.

Thanks! </div></div>
You may not be getting a good neat fit of the case neck on the turner mandrel. If it is too sloppy then a hit amd miss type turning can result. It's best to get an expander die with a mandrel that expands the necks to perfectly fit the turner mandrel. Use lubricant on the turner mandrel to stop seezing STP works ok. Once you get this precision fit turning is much better.
Also polish up the inside of the necks first before you size with and old bore brush with some fine wire wool wrapped around so it just enters the case neck. Then chuck it in an electric screw driver , give it a few seconds polish.

 

[Grump]

Re: On Neck Turning?

RTFP, folks. The fabulous post.

Or get some sleep first.

"turned, sized and loaded necks are showing .01 smaller than the fired case necks"

Or maybe I have to say it a different way: Fired case necks from that chamber show .01 expansion compared to loaded rounds. With the case necks uniformed. Selected either from full-diameter shaved necks, and from necks that got it at least 180 degrees, measuring on the trimmed surfaces on opposite sides of the neck.

Not allowing for spring-back, that tells me that there's plenty of neck clearance in the chamber. It's supposed to be a standard chamber. Semiauto. FC brass.

<span style="font-weight: bold">SO, with that much clearance when turned to about .015 thickness, is there any benefit to be expected from going thinner? </span>I am under the impression that a LOT of neck clearance can be not necessarily a bad thing, but the opposite of the close fit that spawns better accuracy.

Fit to the mandrel is pretty tight--if I don't tumble the cases, then lube is needed to be able to reliably spin anything to get a trim. No wobbling visible or felt.

RCBS neck turning tool. I really need to crank on the case holder tool to even spin them before they reach the blade.

Cased trimmed to 2.005 in Wilson, then full-length resized in RCBS X-Die and they grow to about 2.0075. Die adjusted out about 45 degrees (equals about .005) from hard contact to better match what Springfield Armory says is a 1.631 chamber.

The other notes are to explain that all cases done so far have been thinner at the mouth than next to the shoulder. I do cut literally about one hairs' worth into the shoulder. These cases are now better/more uniform than factory FGMM, and the groups sizes and velocity uniformity with these prepped cases at least match that level of performance.

427: I'm uniforming case necks in search of greater accuracy. Perhaps futile with a gas gun, but the barrel *is* good enough to tell a big difference between ball ammo/reloads, 173-gr M118 (old) bullet reloads, bad reloads with match bullets, and good reloads with match bullets and good match ammo.

I can shoot 1/2-inch 5-round groups at 100 (not 200) with a bolt gun, but this rifle remains stuck at .75-1.25 inch groups with the finest ammo and reloads with the finest bullets in the land...except 155s of any make (well, Sierra, Nosler, Hornady, Lapua and Berger).

 

[Country]

Re: On Neck Turning?

It sounds like you are turning them ok. For an auto I would just skim the necks .