Neck tension- quick question

[D1gger]

So the short version is-if I have the same load, but 1 with a smaller neck busing that both shoot good groups, (.556-.650) would you go with the smaller (tighter) bushing or stay with the larger one?

This is my first foray into precision reloading, I usually just reloaded for bulk, economic reasons, mostly .223 and 9mm. I'm working up a load for my 308 with FGMM cases. I'm getting really consistent .5-.6 groups with a .338 bushing. I tried a .337 and got very similar results. These will be fired out of a Savage bolt gun.
I know too much neck tension is not good, but what are your thoughts on this?
Thanks in advance

 

[Carlos Danger]

I'll say larger (looser) one. Let's see what the experts say.

 

[wvlapua]

I'd pick the one that gives the least amount of vertical at distance. Or Chrono and pick the one that gives the lowest SD.

 

[ShtrRdy]

Are you using the expander ball that is in the die to open the neck back up?

 

[2aBaC̶a̶]

Performance aside. What is the neck size loaded? How easy is it to push the bullet farther into the case by pushing it on something? I've loaded some that spec out fine but was not hard to push in, I was leary that if I dropped one or they got banged around that seating depth could change. Ordered one size smaller.

 

[D1gger]

I haven't been able to chrono the tighter neck, and I can't recall the velocity numbers offhand, but I know my SD was 6 on the larger neck bushing. Neither group showed any signs of vertical stringing, so I'm good there.
I still am running the expander ball on my die, for now anyway.

Thanks

 

[canezach]

I use mandrels to set my neck tension, so I have both the expander mandrel and neck turning mandrel. I know one is 0.001" neck tension and the other is 0.002", but I can never remember which mandrel does which. In my experience, the 0.001" tension has done better on the chrono in several different loads (6 Dasher, 6 and 6.5 Creedmoor, 308, and 300 WM) than 0.002". It's a minimal difference, like an SD/ES of 5/14 compared to 6/17, but better nonetheless

 

[spife7980]

I use mandrels to set my neck tension, so I have both the expander mandrel and neck turning mandrel. I know one is 0.001" neck tension and the other is 0.002", but I can never remember which mandrel does which. In my experience, the 0.001" tension has done better on the chrono in several different loads (6 Dasher, 6 and 6.5 Creedmoor, 308, and 300 WM) than 0.002". It's a minimal difference, like an SD/ES of 5/14 compared to 6/17, but better nonetheless

Expander is .001 larger than the turning mandrel. You expand the brass first so that it then is able to just barely be slid over the smaller turning arbor. The expander is more expansive.

 

[sandwarrior]

So the short version is-if I have the same load, but 1 with a smaller neck busing that both shoot good groups, (.556-.650) would you go with the smaller (tighter) bushing or stay with the larger one?

This is my first foray into precision reloading, I usually just reloaded for bulk, economic reasons, mostly .223 and 9mm. I'm working up a load for my 308 with FGMM cases. I'm getting really consistent .5-.6 groups with a .338 bushing. I tried a .337 and got very similar results. These will be fired out of a Savage bolt gun.
I know too much neck tension is not good, but what are your thoughts on this?
Thanks in advance

I'd say go with the looser one if you are bench or belly bench shooting. If you are moving around a lot and the cases get jarred around a bit, go with as tight a neck as to give you up to .003" tension.

Keep in mind this obviously describes two levels of accuracy. On a bench, DO NOTHING that would hinder accuracy! But, if you are out in a field moving around and stalk shooting targets, or banging around in your 4x4 to get to your shooting area, you want hits, not thousandths differences. And, yeah, I loaded a bunch of "I can just move the bullet with my fingers" loads only to find bullets out and powder all through my loadbox. after going uphill on a sketchy 4-wd road.

FWIW, 264shooter has no issues with accuracy loading his bullets to .004" tension. He did well out to a mile with his 6.5 Creed.

Added: I don't recommend a ball expander. Use the "expander mandrel" (which doesn't really expand, it holds the neck in perfect position while the bushing sizes the brass down around it).

The ball expander has the ability to allow movement of the neck, because it's in "free space", thereby not giving you as tight of concentricity as a mandrel will.

 

[spife7980]

Use the "expander mandrel" (which doesn't really expand, it holds the neck in perfect position while the bushing sizes the brass down around it).

Sounds like you are describing the mandrel in a collet die there vs a typical expander mandrel?

 

[sandwarrior]

Sounds like you are describing the mandrel in a collet die there vs a typical expander mandrel?

Same kind. Not reduced size like a ball expander stem. In fact it’s not really an “expander” it’s just a mandrel that is the correct size for a turned neck. The brass squeezes to the mandrel as the neck goes to that portion of the die. It should act more like a guide than an expander. It won’t take much of an interference fit. Which is why it’s important to get the brass turned correctly.

 

[spife7980]

Same kind. Not reduced size like a ball expander stem. In fact it’s not really an “expander” it’s just a mandrel that is the correct size for a turned neck. The brass squeezes to the mandrel as the neck goes to that portion of the die. It should act more like a guide than an expander. It won’t take much of an interference fit. Which is why it’s important to get the brass turned correctly.

Huh? Whats the same kind as what? And what die are you talking about?

None of the traditional expander mandrels (sinclair, 21st century style and k&m is even more different) go into a bushing sizing die. They have their own dedicated die body.

Traditional expander die body with expander mandrels/arbors, zero bushings. These do not fit into a bushing sizing die. A bushing does not fit into this die body. These are what most people are referring to when they discuss expander mandrels.

Lee collet die, its "bushing" is a collet with fingers that get squeeze smaller around the central mandrel as it bottoms out. The traditional mandrels shown right above do not fit this die.

The typical mandrel that gets discussed here is not the same thing as the lee mandrel.




Expander ball can be installed inside of a bushing die as you said but it is not a mandrel.

You could remove this expander ball sizing down and then you would use the traditional expander mandrel in its own die in its own second step (or the lee collet but they are independent things). The mandrel does not go in into sizer die.




The only thing I can think of thats even remotely similar to wat you are describing is the lyman M die but Ive never actually seen someone use one of them for precision reloading. More for bulk ammo creation where you want the top bit wider for progressive bullet feeding followed by a crimp.

 

[2aBaC̶a̶]

What mandrel dies are you guys using?

Wouldn't an expander ball essentially do the same as a mandrel if it were the same .001 or .002?

Thinking about it I guess the real difference is pushing down on the neck vs pulling it up and possibly stretching brass.

 

[sandwarrior]

Huh? Whats the same kind as what? And what die are you talking about?

None of the traditional expander mandrels (sinclair, 21st century style and k&m is even more different) go into a bushing sizing die. They have their own dedicated die body.

Traditional expander die body with expander mandrels/arbors, zero bushings. These do not fit into a bushing sizing die. A bushing does not fit into this die body. These are what most people are referring to when they discuss expander mandrels.
View attachment 7072972

Lee collet die, its "bushing" is a collet with fingers that get squeeze smaller around the central mandrel as it bottoms out. The traditional mandrels shown right above do not fit this die.
View attachment 7072975


The typical mandrel that gets discussed here is not the same thing as the lee mandrel.




Expander ball can be installed inside of a bushing die as you said but it is not a mandrel.
View attachment 7072979

You could remove this expander ball sizing down and then you would use the traditional expander mandrel in its own die in its own second step (or the lee collet but they are independent things). The mandrel does not go in into sizer die.




The only thing I can think of thats even remotely similar to wat you are describing is the lyman M die but Ive never actually seen someone use one of them for precision reloading. More for bulk ammo creation where you want the top bit wider for progressive bullet feeding followed by a crimp.
View attachment 7072988

The Wilson dies are all made like that. The mandrel is just barely undersized from the unsized neck. As you run the brass up into the bushing, it sizes down to the mandrel. As I stated, it's not really an "expander".

 

[spife7980]

What mandrel dies are you guys using?

Wouldn't an expander ball essentially do the same as a mandrel if it were the same .001 or .002?

Thinking about it I guess the real difference is pushing down on the neck vs pulling it up and possibly stretching brass.

Sinclair, 21st century and k&m are the main players.

The Wilson dies are all made like that. The mandrel is just barely undersized from the unsized neck. As you run the brass up into the bushing, it sizes down to the mandrel. As I stated, it's not really an "expander".

My understanding is that is a decapping rod and not a mandrel at all so I agree with you that "it's not really an "expander".
I dont think the brass is supposed to ever hit it. The wilson dies will only size down and they do not provide any expansion. So I disagree with the statement "The brass squeezes to the mandrel as the neck goes to that portion of the die" If it does that then you have the wrong oversized decapping rod or you have an incorrectly chosen bushing.

As it relates to the OP? Tangentially at best.
OP, be aware that changing your neck tension by removing the expander ball as you currently have installed could cause your load to change from what it is now. How much? Cant say, but it will alter the amount of grip on that bullet.

 

[2aBaC̶a̶]

Just ordered the Sinclair with neck turning mandrel as they were out of the expander.

Is it just a name and .001"difference between the expander and neck turning mandrels or do they actually function different?

It appears the neck turning is basically a .001" smaller expander mandrel.

I've always though of neck turning as something totally different.

 

[spife7980]

Just ordered the Sinclair with neck turning mandrel as they were out of the expander.

Is it just a name and .001"difference between the expander and neck turning mandrels or do they actually function different?

It appears the neck turning is basically a .001" smaller expander mandrel.

I've always though of neck turning as something totally different.

You use both the expander mandrel and the turning arbor in the exact same way, the only difference is the size.

Neck turning is its own thing. Doesnt mean that the case sizing prep tools dont work for normal case sizing though.
For neck turning the expander makes the brass .001 larger than the turning so that the brass just barely fits over the turning arbor without too much resistance when it gets spun during neck turning. Its still tight enough that lubing the turning arbor is recommended to reduce friction/heat. Actual neck turning is diffferent then just the sizing differences.




For sizing purposes you just need to identify which size you would rather have/works better for you.

 

[2aBaC̶a̶]

Yeah, looking for a more consistent ID and a tension that I can't spin the bullet by hand. This looks like the solution.

Wondering at what actual pressure it takes to move the bullet. Is there a neck tension guage? I suppose with the right scale one could simply push down until it moves.

 

[Huskydriver]

Just shoot it...if it groups well with the current bushing who cares. If it doesn't group well get a bushing .002 larger and go again. I feel like guys chase this magical .002 neck tension thing to death. As long as my bullets don't come out of the case, I'm shooting Sub moa, and my necks are not splitting before my webs do it's all in the noise. The current methods are a guide to help you get it there. And unless your Turing necks for a custom chamber, I feel like ton of time is spent fretting over getting .002 perfectly.

 

[spife7980]

Yeah, looking for a more consistent ID and a tension that I can't spin the bullet by hand. This looks like the solution.

Wondering at what actual pressure it takes to move the bullet. Is there a neck tension guage? I suppose with the right scale one could simply push down until it moves.

Thats tough to measure with an actual number, bullet pull is the term for it. To do so you need a guage set up to whatever press you are using to pull them with. Much easier is to measure them going in instead of coming out and to do that you get a hydro arbor press from 21st or k&m which will allow you to measure the seating force.
http://www.xxicsi.com/hydro-bullet-seater.html

 

[2aBaC̶a̶]

Well damn, that's crazy. I can imagine someone's reloading bench looks like a laboratory with all these gadgets.

I'm with @Huskydriver as long as my bullet isn't moving and it shoots good IDGAF what the number ends up being.

 

[flyright]

I experienced superb concentricity, ES/SD's and improved accuracy after switching to a honed Forster FL die with expander removed and a separate Sinclair carbide mandrel that gives 1.5 to 2.5 NT depending on the brass and is always spot on case to case. I use the 2.5 NT on my gas guns but it works fine for bolt guns too. It made everything a bit more consistent overall. No more bushing dies for me. Just my .02...

 

[D1gger]

Thanks for all the great replies. There's so much I don't know.
I do know it shoots well with either load, I think I'll leave the tighter one in for now and see how it goes.

 

[canezach]

What mandrel dies are you guys using?

Wouldn't an expander ball essentially do the same as a mandrel if it were the same .001 or .002?

Thinking about it I guess the real difference is pushing down on the neck vs pulling it up and possibly stretching brass.

Technically, yes. As long as it was still shaped the same, where the expander is basically a small, round ball on something thin, like the decapping rod. It would need to sit inside the brass while the bushing shrunk the neck diameter. I don't think the pull through motion would affect the brass any more than the push through we currently do with the mandrels.

Expander is .001 larger than the turning mandrel. You expand the brass first so that it then is able to just barely be slid over the smaller turning arbor. The expander is more expansive.

Thanks, @spife7980

I just write 0.001" or 0.002" on the plastic sleeve they come in