How to measure neck tension

[mikecr]

The neck expands to release the bullet. The bullet does not slide out of the neck.

This is correct.
And right now we have no way to measure the hoop tension that is bullet grip(purely spring back against bullet bearing).

Seating forces represent only friction. Interference fit means nothing beyond affects to friction. Neither correlating to tension.
It's still useful while we understand it and manage measurement. Consistent seating force makes reaching desired CBTO less of a battle.

I have no doubt frequent process annealing leads to consistent tension, but not necessarily best tension, and not consistent seating forces(friction). It would bring least tension, which is consistent by virtue of least variance. If I were shooting a tiny underbore like a 30br/6PPC that relies on high peak pressure, frequent annealing is not the path I would follow. But a 7WSM, or 260AI, etc.? I could picture consistent tension being more important with these than high tension, as everything is slower/lower in these. Tension comes into play longer.

 

[Bob Sebold]

21st Century has a nice seating press. It has a dial indicator that will give you a pressure reading. Mine reads in foot pounds but I don't know exactly how accurate that measurement is. It is just relative to all the other bullets seated. I keep lighter seaters in front and the ones that seat heaviest to the rear of box and fire them in order.

 

[suberjc]

+1 Bob. I use the K&M but it seems to work pretty well. I know that the case expands to release the bullet but (actually the bullet moves and the case expands simultaneously) consistent force would have to indicate consistent expansion rate everything else being equal. I know that I have been quite pleased with the results after starting to use the gauge. I've never had a bad day in a match when force measurements were consistent round to round.

 

[ShootDots]

The BOTTOM LINE is that we shooters use our own esoteric language to convey an idea we want understood. "Neck Tension", as WE call it, is the measurement of the O.D. of a sized case PRIOR to bullet seating and the measurement AFTER the bullet is seated. If the O.D. of the sized case is .309 and the O.D. of the case AFTER seating the bullet is .310 WE SAY we have 1 thousandths "neck tension". Does it really matter whether we can measure the "tension" or not, JUST AS LONG as we all KNOW what we are referring to? C'mon!

 

[hogan]

Tension is critical to consistent powder ignition. Burn must hold under pressure (tension) until sufficient to release bullet without great amount of continued powder burn. Thus, bullet crimp on max loads, especially w/magnum ctgs.

Release, for best accuracy, must be consistent. Not really urgent in a rifle for bullet position to remain constant; not like with a revolver where bullet-jump can tie up the mechanism. Yet, with consistency comes similar, predictive performance...

No doubt a collet puller could be configured with gauge measuring force applied... weld a 1/2" or 3/4" socket to your press-arm and use a torque wrench...

I am surprised at how many tools aren't marketed to reloaders. Most are halfway clueless of the values and applications that deliver precision, preferring to go anally-retentive to nth degree with variables that mean nothing.


Is a .001" variance between bushings enough? Why not .0005" or .00025" to apply the reduction actually most beneficial?

Why not size necks with the plug positioned inside the neck as opposed to down above the primer? In such manner you get collet efffect which can't move neck position transiting back through on withdrawal...

Use the non-impacting pin holder on your Redding dies? Why not use a universal decapper and avoid the whole issue? It is the inefficiency of the tool variances that can't be overcome, not the value of pin-headed efforts.

Bullet tension, as long as sufficient to prevent shift under recoil is not a major issue, if you haven't worked out and isolated all your variables. Chamber dynamics are more critical than ammo prep, until you understand them; then your ammo prep has real purpose. It ain't your action job or barrel that delivers the precision. Trusting your gunsmith to "know what to do"? You are losing the battle...

 

[Joe Salt]

I guess my neck tension is how it shoots on paper, depending on my wall thickness and size bushing I use. I just keep increasing 1 thou. at a time till I get my best results. Oh and that they all feel the same when I seat them! And I anneal every time.

Joe Salt

 

[mikecr]

The BOTTOM LINE is that we shooters use our own esoteric language to convey an idea we want understood.

ShootDots, the BOTTOM LINE is that 'we shooters' are not all ignorant.
The subject here is "How to measure neck tension?", a direct question, leading to direct discussion about it.
A lot of us know that interference fit, and seating force, are not tension. So we can speak around misunderstandings common among the herd.

Does it really matter whether we can measure the "tension" or not, JUST AS LONG as we all KNOW what we are referring to?

Yes it does matter.
And when 'we shooters' want to understand things, or help others understand things, we don't all reach for fallacies puked from a magazine article.
Do you think the OP wants truths or BS?

 

[ShootDots]

The BOTTOM LINE is that we shooters use our own esoteric language to convey an idea we want understood.

ShootDots, the BOTTOM LINE is that 'we shooters' are not all ignorant.
The subject here is "How to measure neck tension?", a direct question, leading to direct discussion about it.
A lot of us know that interference fit, and seating force, are not tension. So we can speak around misunderstandings common among the herd.

Does it really matter whether we can measure the "tension" or not, JUST AS LONG as we all KNOW what we are referring to?

Yes it does matter.
And when 'we shooters' want to understand things, or help others understand things, we don't all reach for fallacies puked from a magazine article.
Do you think the OP wants truths or BS?

Mike, I will tell you what the OP wants. He wants something, in the strictest sense, that we can not measure directly. So, I gave him what we ALL use... Whether we all use B.S. is up to someone, such as yourself, to bring us to THE EXACT definition so we can all quit using B.S. terms, so no newbie OP has to use our vomit. So now enlighten us all on the exact definition and how we are to arrive at the exact measurement(s) so we all don't stay in the dark and can share in all your knowledge. Since this is a forum to help shooters load and shoot better, we need that exactness, so please share with us..

 

[hogan]

Dots,

I have read that many benchrest shooters can basically seat their bullets with hand pressure on their arbor press type dies. Read that Harry Pope would load his single-shot fired empties with a depriming stem like the Lee jobs that are a basic punch used over a base die w/cavity for spent primer to fall into....

Neck tension doesn't really matter unless you're depending on it...

Consider the precision practice of only partially neck sizing... If your loading a long VLD bullet, to be fired as singly loaded, you can insert the bullet and use the "jam into the lands" to seat and deliver tension. Probably better ignition uniformity this way. Think about instead of sizing the neck as one step, that neck might be sized and then opened up, like an expanding plug used for lead bullets. The brass holds the bullet loosely, but the rifling moves it back into the sized rear half of the caseneck... Thus the bullet orients itself perfectly to the barrel and brass is minimally sized to keep chamber orientation. The pressure builds until it overcomes the lands resistance and then you have bullet transit.

Not going to have a rifle that will be easy to unload using this method, but at a range you fire the round into the dirt or at target to clear the rifle...


Still think the .001" arbitrary bushing size options we are stuck with by mfrs are too large. .00025" would give much more leeway to determine optimum tension.

The BOTTOM LINE is that we shooters use our own esoteric language to convey an idea we want understood.

ShootDots, the BOTTOM LINE is that 'we shooters' are not all ignorant.
The subject here is "How to measure neck tension?", a direct question, leading to direct discussion about it.
A lot of us know that interference fit, and seating force, are not tension. So we can speak around misunderstandings common among the herd.

Does it really matter whether we can measure the "tension" or not, JUST AS LONG as we all KNOW what we are referring to?

Yes it does matter.
And when 'we shooters' want to understand things, or help others understand things, we don't all reach for fallacies puked from a magazine article.
Do you think the OP wants truths or BS?

 

[ShootDots]

Hogan, yes a lot of long range Benchresters shoot with as light of "tension" as they can get and still keep the bullet in place til it gets loaded in the chamber. Then "soft-seating" comes into play. I have a friend who shoots F-Open with us BUT he is really a "short-range" (100-200) yard Benchrester at heart. He shoots a 6PPC and uses bushings that are 4 thousandths SMALLER than a loaded round measures. I do not know if it is a "trait" of the PPC cartridge or not. But he says he uses "4 thousandths neck tension".. I understand what he means.. The vast majority of competitive shooters "know" what he would be referring to.

The neck wall thickness of his brass is turned down pretty thin too, which aides in seating the bullet without too much force, even though he sizes it 4 thousandths UNDER what a loaded round is. Having said that, there must be a WORLD of difference between the short range BR game and it's long range sibling..

 

[trpcboy]

What about a Tinius Olsen pull test machine.

john
Mims, Fl

 

[CaptainMal]

Seat a bullet in an empty case. The push it in on a scale. Look and see how many pounds of pressure it takes to move the bullet in the neck.



I did this a few years ago to show the guys on the Marlin forum you do not need to crimp 30-30 bullets. Seated them without crimp and a .003-.004" interference. Could hardly hold on to the case as I pushed. Some would not even move pushing with 60 lbs of force.

That was a measurement in pounds.

 

[LHSmith]

Short range BR competitors have been using bushings in increments of 0.0005" for years. They are carbide and go $40 a pop.....but because they are precision ground the bore is true to size,concentric to the OD, and the ends are perpendicular to the bore.

 

[K22]

Very interesting reading these post but it makes me glad that I'm not a bench rest shooter.

 

[CHROME]

In my original post...how to measure neck tension....I am interested in how you ACTUALLY measure neck tension. I don't post on here much at all...I am not a newbie to shooting. When you measure a loaded round and then go 1 to 2 thou. smaller, in my opinion, that is not measuring neck tension. What was the original neck tension before you added 1 to 2 thou more??

If you measure the wall thickness of your case, multiply it by 2, then add it to the outside dimension of the unloaded resized case, this would give you the actual dimension of the mouth of the case, better known as the hole size.

Ex. .012 case thickness, x2 =24, minus 266 which is the OD of the resized case equals 242. If you shooting 6mm which is .243, that would give you a neck tension of .001.

I am interested in seeing how others measure this, in my opinion, very important aspect of precision shooting.

Am I off base ??? Thanks, in advance, for all your input !!!

 

[mr45man]

I have one of these:
http://www.kmshooting.com/catalog/arbor-press/arbor-press-with-force-measurement-option.html
John H.

 

[Dos XX]

Neck constriction is probably a better description than neck tension, though I agree with others that said it doesn't matter what you call it if everyone in the conversation understands what is meant.

I use a micrometer if I want to see the difference in neck od sized with say a bushing versus a mandrel and the difference might be <.001. If I'm not after that fine of a measurement, I use my calipers. Either way, I measure the neck od of a loaded round. Measure the neck od of a sized case. Subtract.

 

[LHSmith]

In my original post...how to measure neck tension....I am interested in how you ACTUALLY measure neck tension.h is .243, that would give you a neck tension of .001.

I am interested in seeing how others measure this, in my opinion, very important aspect of precision shooting.

Here's how I "measure" neck tension" for Short Range BR : I measure by "feel" -i.e. how much resistance is felt when inserting the bullet using a Wilson seater die and a lightweight arbor press (as made specifically for reloading). The trick is to develop a technique using the press handle that reduces the mechanical advantage of the lever so as to make feedback more sensitive.
As far as assigning numbers to N.T. -I don't correlate anything meaningful to those numbers> I test loads with different bushings in an attempt to achieve as wide a tune window as possible for a given set of range conditions that I anticipate to encounter on match day.
If a case neck offers too little resistance, I pull the bullet and powder and size it with the next size smaller bushing, mark it, and verify it goes to the same POA as the rest of the cases before it finds it's place back in rotation for use in a registered match. A case that offers more resistance than the norm is designated as a "fouler" and so marked by color coding.
BTW, accuracy-wise optimum NT is powder dependent. Vihtavouri N-133, perhaps the most popular SR BR in the last 15 years shoots best with a lot N.T. which seems to be a universal fact in all comp.rifles when 133 is used.