Neck Tension vs Accuracy

[jlow]

I think it is more complicated than you think. Some of what you say is true but it is not as clear cut in every instance.

Take for example of a case (call it CASE 1) that has been annealed – it is now softer and so it can be downsized more using the same bushing. So compared to another identical case (call it CASE 2) which has not been annealed and so more spring back and when downsized with the same bushing has large neck ID. Ignoring seating force for a minute and concentrating on grip strength because that and friction is really what matters when the round is fired.

In the first situation, you have a CASE 1 with a smaller ID but slightly softer neck so less spring back ability. Compared to another case (call it CASE 3) that has the same spring back as CASE 1 but an ID that is similar to CASE 3, because it has a larger ID, it will have less neck tension.

So in terms of neck tension we known CASE I > CASE 3 but is CASE 2 >CASE 1? It certainly has more spring back but it’s neck ID is in fact larger…. Another question is how does the amount of reduction in ID plays into this? Is it always the same regardless of whether we are using a bushing that theoretically gives a 1 thousands reduction vs. one that gives a 5 thousands reduction? How about the degree of difference in spring back or degree of annealing.

So I think it can be pretty complicated but I do agree with you that the reduction in ID and its apparent effect on seating force can be misleading.

 

[johara1]

I have trouble with holding a bullet that has a pressure ring .0005 larger than the shank. If seated in it shoots the best but if you open the action it will pull the bullet. There is no way to verify the seating depth, i anneal, tried more neck tension still pulls the bullet. I even tried new unfired cases still pulled the bullet. Spring back remains the same, i seated deeper to send the heel trough the sized part of the neck and on all of them you could push the bullet in with your fingers. Annealing gives you uniformity no more no less……… jim

 

[LHSmith]

Theories make good discussion, but I give credibility to those who have experimented and have found results to help them succeed competitively. These winning competitors, IMHO, possess knowledge at an entirely different level than a non- competitive shooter. The very fact that they have learned to shoot in various conditions (wind, mirage, and light) is what give them credence. These guys (gals) have the uncanny ability to call vitually every one of their shots (learned through thousands of rounds)......who better to diagnose fliers from a new batch of rounds as reloading related? Don't get me wrong, minutia can be good. The best shooters I know,are extremely anal about each case is prepped and each round is loaded in the "exact same manner".....they just know which steps really matter.
This experience brings them to a place that allows them to arrive at a match with a gun they can "trust" ( a process which may have taken them through several barrels). How many of us can truly make that claim?

 

[jlow]

There is no doubt that people who reloads and shoots well in competition have excellent knowledge that all of us can learn from, however, there is no reason to believe that they are the only ones who can contribute to the understanding and overall knowledge base which can advance the sport. Thinking this way is pure elitism.

The truth is reloading is an inexact science and even the best shooters who excels in the highest level of the sport will tell you they do certain things to get there but they will also tell you frequently that they do not totally understand why it works and that they have not scientifically tested and determined the reason why those technique works.

When I worked as a research scientist, even with a Ph.D. degree and 30 years of experience on the bench I have received insightful ideas from young interns who work in my laboratory. Those who think they know everything and nobody can teach them anything suffers the consequences….

 

[johara1]

jlow, If you seat a bullet with in one pound of seating force plus holding my other tolerance the same my ES. will drop to 2-3 area. My necks are annealed seating force was 20-21 lbs. Bullets are trimmed and pointed, bearing surface is held to zero and spun on a Juneke machine and powder is weighed on a GD503 to .01gr. This the best i can do, does it work……….. yes …… jim

 

[jlow]

Your point?

 

[johara1]

Your point?

Trying to reason it out the way you are approaching the issue was done many times and this is what works. Neck tension is tied to other variables. I may not have a PHD but i feel equal to anybody and i can look on the wall to justify the statement. Neck tension is part of how you clean your necks the same how you anneal and loaded round diameter used in your chamber neck diameter. Spring back on the neck in a chamber is .001, but spring back on a bullet seated in the neck is .0005….. why………jim

 

[jlow]

I agree with most of what you say and no offense intended but you kind of lost me in that last sentence. Not sure what your question is?

 

[BoydAllen]

The problem becomes more challenging when groups indicate that a given set of components, particularly the powder, produce better accuracy with higher seating force. In the short range benchrest game, 133 is known to have this preference, and loads that have the lowest ESs may not produce the smallest groups. On the other hand, I think that it can be said that having more uniform seating force is always an advantage. With thin necks, and the need for keeping seating force as high as one can, annealing is not an option, and sorting becomes the preferred method. For that , one of the presses that put a number on the force required would seem to be an advantage, those being, K&M and 21st Century.

 

[daniel brothers]

good stuff Guys.... what a wealth of information... keep it coming.

 

[Cassidy]

Thanks for the explanation Boyd.

 

[LHSmith]

jlow- we keep having the same conversation. If your goal is to write a book or thesis on proper reloading techniques for maximum accuracy (might be a little late to the table on this one)....have at it. Just note that most of those who have preceded your ambitions were nationally ranked competitors (Boyer, Newick, and Ratigan to name a few).
There simply is no shortcut to understanding the hows of obtaining maximum accuracy without firing thousands of rounds so that condition reading and shooting form become second nature.
Figure out the how's before you attempt to reason out the why's.......shoot more!

 

[LHSmith]

The biggest improvement to ones accuracy isn't in the difference between a thou , 2 thou,( or 3 for that matter) neck tension ...it's learning how conditions affect the bullet....with that rifle, that load in that specific period of time.
Perhaps if we all shot in a tunnel, some things could be more easily explained. But in the real world, the conditions are constantly changing making any reasoning more complex.

 

[johara1]

I agree with most of what you say and no offense intended but you kind of lost me in that last sentence. Not sure what your question is?

When you talk about spring back, i see two different amounts. One was in a fired case in a chamber neck is a .001, cases fired in my .266 neck come out .265 ….. .001 spring back. When seat a bullet with a pressure ring .0005 larger than the shank size, it will not grip the bullet after the pressure ring passes through……… .0005 spring back. after it is fired it all ends up at .265……… jim

 

[johara1]

The problem becomes more challenging when groups indicate that a given set of components, particularly the powder, produce better accuracy with higher seating force. In the short range benchrest game, 133 is known to have this preference, and loads that have the lowest ESs may not produce the smallest groups. On the other hand, I think that it can be said that having more uniform seating force is always an advantage. With thin necks, and the need for keeping seating force as high as one can, annealing is not an option, and sorting becomes the preferred method. For that , one of the presses that put a number on the force required would seem to be an advantage, those being, K&M and 21st Century.

Boyd, You are referring to short range because at long range, high ES. is vertical and i use thin necks and only use .002 NT. The more neck tension .003 or .004 give me erratic seating pressure. I tried higher NT. to try to hold the bullet but it was futile…… jim

 

[BoydAllen]

No argument from me on any of that. All good information. I think that the longer, higher sectional density bullets in the long range games tend to negate the need for higher seating forces by their greater inertia.

 

[jlow]

LHSmith – What’s with the childish taunts? Really, do we have to go there?

Here is the thing that I don’t understand. Why does it bother you so much when I ask questions to learn more about reloading?

There are a lot of helpful people on this board who has helped me and others in the past and I am frankly very thankful – my reloading would not be where it is today without their help. That is not to say that it is in any way perfect – thus the questions. The problem here is I understand that there are some don’t want to or cannot share their knowledge. Hey, I understand, you spend a lot of time and money learning those secrets and you don’t want your potential competitors to learn of them and beat you. However, no one has the right to discourage and stop another person from doing their best to learn the same thing. This again is a technical reloading board and its whole purpose is the exchange of information and for people like me to come and learn. So that type of behavior has no place here.

Yes, I have an advanced science degree but it is not in reloading so I am like the majority of the people who comes to this technical reloading board i.e. I am here to learn. What I have learned in my 40 years career is that you learn by asking questions. I am polite in asking questions and if I am wrong in any of my assumptions, I welcome people to point them out – again this is how I learn. If this method of learning really bothers you, I am sorry but you really have one choice– please ignore it and move on.

Johara1 – Not really sure I can help but here goes. So certainly if your case is fired in a chamber .266 in diameter, it will as you say spring back .001 and give you a .265” neck external diameter – that is pretty normal. Your bullet has a .0005” pressure ring and as it pass through the case, it will stretch the case slightly but if the diameter of the bullet is either smaller or the same as the internal diameter of case neck, once the pressure ring pass through, it will not grip the bullet. Even if the diameter of your bullet is slightly greater than the internal diameter of the neck, say around .0003”, the spring back after the pressure ring has gone through may not be enough (i.e. .0005”) to grip the bullet. Is this your question? Sorry but hard to come up with more until we know the other dimensions like neck thickness, bullet diameter, etc.

 

[johara1]

Boyd, iI thing my problem with neck tension is unique, Spencer bullets shoot great but if i could figure out how to grip the bullet better so i could open the bolt and verify my seating depth i could do even better. The shape of the bullet has something to do with it, when you make contact with the lands so does the grooves,360 degrees. It never goes away, it may shin up a little but it is always there. Throat advancement is minimal. Don't get me wrong it's not bad jumping but it shoots like a PPC. in.010….. .040's isn't hard to get, but it makes you crazy because you can't verify the seating depth. So jumping them is the alternative ……… jim

 

[johara1]

jlow, My bullet diameter is .2432 on the shank and .2437 on the pressure ring. My neck thickness is .0102……. jim

 

[BoydAllen]

With the short range benchrest bullets that I have tried, which include one or more that contact the rifling with an 9R ogive segment, I have never had a problem with getting a continuous circle (To clarify, I always get rifling marks by themselves.). The only examples that I know of where this happened were friends that did not know that they had some hard carbon built up in their chambers' throats. You may have mentioned it in another post, but since I can't remember, do you have a bore scope, or know someone with one, so that you can take a look at your chamber's throat? Also, what Spencer bullet are you shooting, and what is the ogive number? Do you know your chamber's freebore diameter and leade angle? Something strange is going on here. Do you get the circle with other bullets, or just that one?