Does Neck Tension matter ?

[nettlle]

I am neither judging or criticizing. Only asking questions.

 

[JFrank]

I may just

I am?

While too light of tension may effect ES/SD and vertical dispersion , they can certainly be a seperate topic as many targets show positive compensation and small groups yet have terrible ES/SD.

 

[nettlle]

There is nothing complicated or really expensive about it.
Go gages are not required
Annealing is not required
Neck turning is not required
Mandrels may be required if you don’t have a bushing type die
A minor selection of bushings if you have a bushing die
Seating force gages are not required
Mics are not required

All a person needs are a mandrels set or bushings and a paper target along with a desire to learn something.
I’ve already posted a very good testing format, neck tension is a very underrated but important part of load development that can have a huge impact on precision.

What would be my goal? How would I know if the neck tension I have now is not good enough?

 

[JFrank]

I am neither judging or criticizing. Only asking questions.

I use a bushing die with four bushings to choose from, I’ve cut my group size in half by sending a few rounds down range and interpreting results.
Not every one will see that amount of change but it’s simple enough to test a bit.

 

[nettlle]

There is nothing complicated or really expensive about it.
Go gages are not required
Annealing is not required
Neck turning is not required
Mandrels may be required if you don’t have a bushing type die
A minor selection of bushings if you have a bushing die
Seating force gages are not required
Mics are not required

All a person needs are a mandrels set or bushings and a paper target along with a desire to learn something.
I’ve already posted a very good testing format, neck tension is a very underrated but important part of load development that can have a huge impact on precision.

What would be my goal? How would I know if the neck tension I have now is not good enough?

 

[JFrank]

What would be my goal? How would I know if the neck tension I have now is not good enough?

The best way I know if is to set up a powder ladder test using a couple rounds of each powder increment. Using a couple different bushing sizes , color the ogives with a sharpie and send them at a target the furthest distance you can find.
Judge the overall performance ( overall group size ) .
Notice here that the top right target is an example of just a .001 smaller bushing than the lower left target, now notice that the overall group is half the size yet my node of approx 30. 7 hasn’t really changed on either group. Just to re state that if your rifle is already on the preferred amount you’ll simply confirm you’ve done a good job.

 

[JFrank]

I think it’s time I let this thread idle down, if a guy wants to advance his program , testing bullet hold is certainly a good place to start of finish.

Thanks to all the members for their input I hope this helps someone somewhere sometime.
Shoot small
J

 

[Walkalong]

I may just

While too light of tension may effect ES/SD and vertical dispersion , they can certainly be a seperate topic as many targets show positive compensation and small groups yet have terrible ES/SD.

It can, that’s a fact, especially pistol/revolver ammo.

With my 6PPC we used light neck tension, but were into the lands to get that good start pressure/burn.

I mentioned that method in the previous yhread.

 

[JFrank]

While I could probably improve my ES/SD numbers by using a lighter grip on the bullet and perhaps annealing, my testing shows that my groups would suffer and in the game I play group size and score are all that matters. Same thing in the short range/ point blank game where the target is king and no points are awarded for favorable chronograph numbers. Case in point my posted target below has poor numbers yet my 500 yard group shows virtually no vertical dispersion.

 

[Walkalong]

While I could probably improve my ES/SD numbers by using a lighter grip

Tighter grip will improve them if you’re too light. It needs a certain amount of neck tension if it’s not getting help being into the lands.

 

[JFrank]

Everytime I think I have this stuff figured out I find out something new, this is some testing done by the fella I posted a link to. shot at 1000 yards.

(The loads are identical other than neck tension and OAL, they were all jumped over .020”, the no tension loads were probably .020” to .050” jump. I’m visualizing the light tension bullets moved to a touch/jam point very rapidly in the firing sequence. Aim point is the same on all shots.)

Maybe this just re enforces the thought that when jumping a guy might be able to use less hold. IDK

 

[Walkalong]

As I have posted many times, one group or set of groups means nothing. It has to repeat over time. Or shoot 20/30 shot groups and have the skill/focus to do it fairly.

 

[Varminterror]

It’s pretty simple for me:

1) Too little neck tension and we don’t get reliability in primary ignition, so even if the average is in tune, any variability in ammunition or environment will kick the tune off of the edge of the table. At light neck tension, a little change is a large proportionate change, so it’s harder to control consistency (hence folks jamming bullets when soft seating, or jamming in general).

2) Too much neck tension and we’re deforming our bullets, which either means poor bore seal or jacket/core malformation, influenced BC, etc…

3) For uncontrolled or wildly inconsistent neck tension, we’re somewhere, anywhere, and everywhere on that spectrum.

 

[GeoDudeFlorida]

Everytime I think I have this stuff figured out I find out something new, this is some testing done by the fella I posted a link to. shot at 1000 yards.

(The loads are identical other than neck tension and OAL, they were all jumped over .020”, the no tension loads were probably .020” to .050” jump. I’m visualizing the light tension bullets moved to a touch/jam point very rapidly in the firing sequence. Aim point is the same on all shots.)

Makes perfect sense to me.
Q: do “revolver cartridges” really need a roll crimp? If so, why?
Do they need any crimp? Do they need any neck tension? As long as the throats are tight, and the recoil energy is minimal, does there need to be any neck tension on a revolver cartridge?
Consider this:
I load several varieties of non-cannelure bullets in some heavy magnums for revolvers (that’s nothing special, lots of reloaders do) and only use a taper crimp or an FCD for the nearest sized rimless cartridge - which is also a taper but not a fixed taper; it has some adjustment. I don’t bother measuring the tension or pull because I know from load development using an RCBS collet puller that the recoil energy is not enough to dislodge the bullet. For this example, is the neck tension change from plain seated to tapered really necessary?

Think about what’s happening before answering.

The neck tension matters but in some cases (QED) less is more and none is better. The reverse is also going to be true. It just depends.

 

[Varminterror]

As I have posted many times, one group or set of groups means nothing. It has to repeat over time. Or shoot 20/30 shot groups and have the skill/focus to do it fairly.

Ditto.

I’ve posted many, many times around here - low count shot groups have lead far too many shooters to believe they found a node when all they found was coincidence. Noise.

The low shot count group based load development method has likely been one of the most permeating and enduring Faustian memes of the last century. Folks in pursuit of knowledge make a deal with the devil, and in this path, condemn themselves to misery. Too many folks find confidence in coincidence.

 

[JmacD]

I’ve been lurking on this thread. Lots of good information. And not trying to open a keg of worms. But,! Is “tension” really a “.002” type measurement? Isn’t it more of a resistance measurement? I’m no expert and I only worked in a machine shop enough to be dangerous. But the temperature of your brass(especially in my range sessions ranging from -8 through 102) could make that much difference. Right? You can make 1 time fired lapua and 4 time fired RP brass measure that .002 measurement, but actual tension is more metallurgical, right? Or am I off in the rhubarb?

 

[JFrank]

As I have posted many times, one group or set of groups means nothing. It has to repeat over time. Or shoot 20/30 shot groups and have the skill/focus to do it fairly.

Interpreting test results plays apart in this as well, personally I don’t require 20-30 shot groups to find a node, granted I continue to tune to the fine edges as conditions change through out the season but finding a node center of a basic tune is quite easy and repeatable. Guys make it far too complicated in my opinion.

 

[Varminterror]

Q: do “revolver cartridges” really need a roll crimp? If so, why?
Do they need any crimp? Do they need any neck tension? As long as the throats are tight, and the recoil energy is minimal, does there need to be any neck tension on a revolver cartridge?
Consider this:
I load several varieties of non-cannelure bullets in some heavy magnums for revolvers (that’s nothing special, lots of reloaders do) and only use a taper crimp or an FCD for the nearest sized rimless cartridge - which is also a taper but not a fixed taper; it has some adjustment. I don’t bother measuring the tension or pull because I know from load development using an RCBS collet puller that the recoil energy is not enough to dislodge the bullet. For this example, is the neck tension change from plain seated to tapered really necessary?

I’m not sure this reads the way you’re wanting.

What I read here:

There are 3 different ways I have created substantial and sufficient interference fit to hold a bullet into a revolver case, and they all work (to whatever unmeasured standard).

That doesn’t read to me as the same as saying neck tension doesn’t influence ammunition performance, especially in regards to precision.

 

[JFrank]

I’ve been lurking on this thread. Lots of good information. And not trying to open a keg of worms. But,! Is “tension” really a “.002” type measurement? Isn’t it more of a resistance measurement? I’m no expert and I only worked in a machine shop enough to be dangerous. But the temperature of your brass(especially in my range sessions ranging from -8 through 102) could make that much difference. Right? You can make 1 time fired lapua and 4 time fired RP brass measure that .002 measurement, but actual tension is more metallurgical, right? Or am I off in the rhubarb?

While I’m no expert on metallurgy, I can say that a guy can have .004 dimensional difference between bullet OD and neck ID and still have smooth consistent seating force by reducing friction ( brush the inside of the neck prior to seating) or have .002 difference with a lot of friction and seating resistance by leaving the rough carbon untouched in the necks, seating force gages can be deceptive.

 

[Varminterror]

Is “tension” really a “.002” type measurement? Isn’t it more of a resistance measurement?

Classically, “neck tension” is defined as the difference between the sum of the dimensions of the neck wall thickness (2x) and the bullet diameter, minus the finished cartridge neck diameter. Better named, it would be “bullet/caseneck interference fit,” or “bullet/neck crush.”

I speculate that this has been so broadly accepted because 1) we have no means of actually measuring the gripping force of the case on the bullet, 2) we have no means of actually measuring the tension (hoop stress) within the case neck around the bullet, 3) the overwhelming majority of reloaders have no means of measuring other proxies such as seating resistance or pulling resistance, and 4) even among those which do, the experimental control to validate seating or pulling resistance is highly complex (in other words, if I seat faster or slower, I can influence the peak force measured during the stroke).

So overall, the proxy of accepting the interference fit dimension kinda makes sense. Everyone can measure it, and nobody can really screw it up.

 

[JFrank]

Makes perfect sense to me.
Q: do “revolver cartridges” really need a roll crimp? If so, why?
Do they need any crimp? Do they need any neck tension? As long as the throats are tight, and the recoil energy is minimal, does there need to be any neck tension on a revolver cartridge?
Consider this:
I load several varieties of non-cannelure bullets in some heavy magnums for revolvers (that’s nothing special, lots of reloaders do) and only use a taper crimp or an FCD for the nearest sized rimless cartridge - which is also a taper but not a fixed taper; it has some adjustment. I don’t bother measuring the tension or pull because I know from load development using an RCBS collet puller that the recoil energy is not enough to dislodge the bullet. For this example, is the neck tension change from plain seated to tapered really necessary?

Think about what’s happening before answering.

The neck tension matters but in some cases (QED) less is more and none is better. The reverse is also going to be true. It just depends.

Maybe pistols just don’t shoot far enough to notice any difference on the target, or it has something to do with bottle neck cartridges. I really don’t know.

 

[JFrank]

As I have posted many times, one group or set of groups means nothing. It has to repeat over time. Or shoot 20/30 shot groups and have the skill/focus to do it fairly.

Maybe this points out that group shooting isn’t the best way to develop a repeatable load ?
Whoops’ went off topic, sorry walkalong…

 

[JmacD]

Classically, “neck tension” is defined as the difference between the sum of the dimensions of the neck wall thickness (2x) and the bullet diameter, minus the finished cartridge neck diameter. Better named, it would be “bullet/caseneck interference fit,” or “bullet/neck crush.”

I speculate that this has been so broadly accepted because 1) we have no means of actually measuring the gripping force of the case on the bullet, 2) we have no means of actually measuring the tension (hoop stress) within the case neck around the bullet, 3) the overwhelming majority of reloaders have no means of measuring other proxies such as seating resistance or pulling resistance, and 4) even among those which do, the experimental control to validate seating or pulling resistance is highly complex (in other words, if I seat faster or slower, I can influence the peak force measured during the stroke).

So overall, the proxy of accepting the interference fit dimension kinda makes sense. Everyone can measure it, and nobody can really screw it up.

You’ve voiced (much more eloquently) kinda the conclusion I came to. But there’s part of me that just gets bothered by calling it “tension”, when that’s not really what it is…

 

[Soonerpesek]

Neck tension matters. How much varies a lot on application etc.

We'd have to differentiate what applications.

The neck tension matters but in some cases (QED) less is more and none is better. The reverse is also going to be true. It just depends.

Both these statements are undeniably true and, for the most part, say the same correct thing.

Why would only 1 of them be questioned...?...................hmmmm

 

[jmorris]

Q: do “revolver cartridges” really need a roll crimp? If so, why?
Do they need any crimp? Do they need any neck tension? As long as the throats are tight, and the recoil energy is minimal, does there need to be any neck tension on a revolver cartridge?

Once you align variables in such a way, they don't mean as much to me. If you want one case (pun intended), I have some 30+ year old CCI shot capsules that are pretty fragile and crack with much crimp at all these days, wound up not putting much crimp on them because of this. They get loaded as 1 shot round and the remaining holes filled with solids. The shot load is the one that has to go first or recoil will pull it enough to stick out of the cylinder so it is no longer free to rotate.

It has to repeat over time.

As well as under various circumstances or it obviously matters.