Neck Tension

[IHFarmer07]

I'm also somewhat new to reloading, it'll be a year in December. Anyway I've been playing with a .224 Valkyrie and it's a good thing I started with this small of one or else it would've been more expensive than it already is. Here is what I do is deprime, clean, anneal, size, trim debur/chamfer, run a Sinclair .002" under mandrel in, prime and then load to the kernel of powder. I do this every time and I've been finding that things are still not getting what I think I should get on es/sd. So I have been playing with neck tension lately because I have noticed on some cases that seating a bullet takes little more force and I've been watching this and every one that had more tension had better speed than the ones that had a light force and velocity where it should be at.
I finally did some checking on tensions and testing a forester fl die with the sizing stem a some with out and some brass that had necks turned and some without and no mandrel. The runout with the .224V using starline brass with the sizing stem in was around .001-.002 run out on both the neck turned and non turned brass using a Sinclair brass run out tool and a starrett gauge. Now, I tested the forester FL sized brass neck turned and not with out the sizing stem and I got less than a .001" neck run out. Shot them all which was a small sample size, 5 rounds of each process and the es and sd was worse with the sizing stem in in fl sized brass w/o a mandrel and groups weren't that good. I got to the neck turned, no mandrel, no sizing stem and my es/sd was really good, best I have ever gotten, single digit es and sd!! The no neck turn, no mandrel, no sizing stem wasn't as good but better than the sizing stem brass. So now I'm going to test all 10 neck turned brass and non turned with the process that turned out good and test again. I also ordered a bushing die to see if I can get more/less neck tension but it's looking like my gun likes more tension than less as I tested that also. Seriously considering buying a k&m neck tension mandrels and their die to hold them unless I can have them fit my Sinclair die for mandrels or sand the mandrels down to the neck tension I want.

 

[DocDoc]

I think we may be kidding ourselves with some of the neck tension ideas. If the bullet expands the resized neck, I am not sure it makes much difference if it expands the brass 0.001 or 0.003 on insertion on the strength of the hold on the bullet. How elastic is the brass?

 

[Mikecr]

You're right DocDoc. Necks spring back ~1thou (Max). Tension amounts to a force within that spring back against seated bullet bearing (grip).
Downsizing to leave interference anymore than this is merely undone by bullet seating.

Almost nobody here understands that interference fit does not equal tension.
Seating/pull forces (friction) do not equal tension either.
There is just a lot of bad info in this thread

 

[tdot]

If I pull a bullet, from a case that I have sized .002" under caliber, it does not remain static at the size of the bullet. It is smaller, best I can measure is somewhere around .001" under caliber. Is this not tension? If it was a friction fit, would it not be the exact caliber size of the bullet.

 

[SealT5]

Are you talking about bullet or neck runout on unturned brass?

I know some claim to get better runout this way but I have tested it with multiple cartridges and brass manufactures with Redding and Whidden dies and I always get less runout with bushing dies and no expander ball. I revisit it every couple of years but the bushing with no mandrels always wins for me. It can't hurt to experiment.

 

[SealT5]

.002" is thrown around a lot. Yes it is a good generic starting point but do not assume more neck tension means less accuracy. I've seen numerous shooters claim as much as 8 thou tension on their competition load. I currently have a 22 dasher that like 5 thou.

Joe S.

 

[bigedp51]

Below is a 9mm that was resized with a Lee undersize die that is .002 to .003 smaller in diameter than a standard die. You can see the case has plenty of bullet grip and the case is wasp waisted below the bullet. You can also see where the bullet stops inside the case and the increased bullet grip.

Below is a .223 Lyman type "M" expander and .003 bullet grip or neck tension depending on brass spring back. The .226 upper section springs back about .001 and allows starting the bullet with just your fingers. This alow straight inline seating and reduces bullet runout.

 

[FURMAN]

Are you talking about bullet or neck runout on unturned brass?

No. seated bullet runout/concentricity.

 

[Mikecr]

If I pull a bullet, from a case that I have sized .002" under caliber, it does not remain static at the size of the bullet. It is smaller, best I can measure is somewhere around .001" under caliber. Is this not tension? If it was a friction fit, would it not be the exact caliber size of the bullet.

Yes the brass springs back nearly 1thou. That distance is not tension, that dimension is not tension.
The FORCE of that spring back against .xxx" of bullet bearing area is what grips bullets. That's tension, and currently, you, nor anybody here, has any way to measure it.

 

[FURMAN]

Yes the brass springs back nearly 1thou. That distance is not tension, that dimension is not tension.
The FORCE of that spring back against .xxx" of bullet bearing area is what grips bullets. That's tension, and currently, you, nor anybody here, has any way to measure it.

99.9% of everyone in the history of reloading understand that we use the amount of sizing to speak of the tension placed on the neck. You I am sure know that yet you choose to try to come show everyone how smart you are. Someone inevitably feels the need every time this topic comes up. Anyone who knows anything understands that the lubricant on the inside of the neck and the bulllet, the amount of bearing surface actually touching the inside of the neck, and the clamping force applied to the bullet from the neck all add up to actually force holding the bullet in and yet here we are...

Seating force measured with a dial indicator has been tested by many to not have any detectible affect on accuracy. If you chose to use that method power to you. The rest of us will continue to discuss this they way we always have most likely will until long after I am gone.

 

[Dirtrax]

Yes the brass springs back nearly 1thou. That distance is not tension, that dimension is not tension.
The FORCE of that spring back against .xxx" of bullet bearing area is what grips bullets. That's tension, and currently, you, nor anybody here, has any way to measure it.

I've been arguing this for for years. The info is readily available in manuals and papers speaking to the properties of brass. Annealing or not has an effect. The specific alloy (brand) does as well. Think "elastic" vs "plastic".

 

[tdot]

Yes the brass springs back nearly 1thou. That distance is not tension, that dimension is not tension.
The FORCE of that spring back against .xxx" of bullet bearing area is what grips bullets. That's tension, and currently, you, nor anybody here, has any way to measure it.

Ok, so then how do you propose to measure the Force? I dont have a single instrument that measures the kN of Force that the brass is applying to the bullet. Nor as you pointed out does almost anyone else here. (It could probably be done with a precise measurement of PSI in a pressure vessel or possibly a strain guage, so I wont say that no one here can measure it) but I will concede that it's very difficult.

For that matter, to discuss a friction fit is almost inherently useless as well, we dont have a way to measure this easily. Carbon in your neck? Left over lube? That all changes the coefficient of friction.

So are you simply offering an English lesson, or are you proposing a different method for measuring the neck tension? Or what exactly are you trying to explain to us?

 

[Mikecr]

I'm pointing out that our reloading mob is lost w/regard to neck tension.
Those merchandizing the latest gizmos for annealing are lost as well.

What we have here is hoop tension, providing a variable force to grip bullets. There is more to this than simple downsizing. We have thickness variances, and shoulder angles contributing, and brass hardness, and length sized, and bearing area seated, and this -vs- that, etc.
What we need to measure this is an instrumented collet system to measure a neck force which is countering expansion -to release a bullet. The collet system would expand a neck via hydraulics or pneumatics until a neck has reached a standard growth of say 1/10thou (bullet fully released). On release of pressure the neck springs back to that established with your sizing plan.
This would then tell us we have a neck providing 22psi of grip, versus a mean average of 28psi (just for example). That's comparative, and you could calculate actual tension given xxx square inches of bullet area gripped.

Someday we may have it, or we may never have it. With all the copying of products brought to market, and customer loyalty at an all time low, this is not viable to even develop at this time. The gains cannot equal the cost (right now).
So for a long time past into future, we're stuck in a rut of delusion and disinformation.
Very similar to the base to ogive (BTO) hogwash this mob wastes resources with..

You might wonder why I would refer to these situations as reinforced by a mob.
Well, a mob is a gathering to group thinking. And intelligence drops with numbers.
So when I see nearly everyone in a group declaring something consistently, while nobody in that group can provide any basis nor understanding for, I recognize it as the murmuring of a mob. Any single one of us in the mob is actually more intelligent than the mob as a whole. So never be afraid to think for yourself.

 

[6MM06AI]

Lots of great info on this and I always like reading everybody's ideas. I guess I'm that worried about neck tension and more about consistancy from case to case, but had a thought of a way to measure it. Put a loaded shell into your press, use a grip and pull bullet puller and use a scale attached to your press handle to pull the bullet it would give you a little bit of an idea of tension. Of course every press can and would be different. Just something for you to try. Good luck and safe shooting!