Neck Tension / How much do you like and why?

Discussion in 'Reloading Forum (All Calibers)' started by gilream, Jun 30, 2010.

  1. gilream

    gilream

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    I've had conflicting advice on this question. Some folks recommend a light neck tension of .001 and some recommend between .002 and .003

    I'd like to know what you guys use and why.
    Thanks..Mike
     
  2. glo

    glo

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    I use .002. I think this is due to the amount of spring-back the brass has at the neck. I anneal my case necks every 3rd firing or so. Some guys anneal after every firing, some wait a few like me and I supposes some never anneal.

    An annealed case neck has very little spring back and a hard worked neck as a lot of spring back.

    There are some shooters that use so little of neck tension as to allow the bullet to seat fully, when chambered right up against the lands.

    Mostly shooters use a neck tension that gives them the best group at the distance being shoot. Therefore, some rifles will like .001 neck tension, some will like .002 to .003, and some will digest anything. Few rifles will ever shoot the same.
    glo
     
  3. spclark

    spclark Gold $$ Contributor

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    Glo said it - you need to work out what works for your style of shooting & equipment.

    I know some benchresters who repeatedly load the same case(s) without resizing. Obviously this calls for VERY solid knowledge of the chamber dimensions of their barrels! I'd never attempt anything like this with my stuff.

    I myself like between .001" - .002" for reloading Palma brass (whether turned or not but I do anneal every 2nd firing) but a little more like .002" - .003" for space gun uppers in 6mm.

    I have a sneaking hunch that if one shoots factory brass with heavy neck wall thickness (≥ .014" in my experience) doesn't neck turn at all & anneals seldom if ever, neck tension is going to be unpredictable....
     
  4. GermanS1

    GermanS1

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    I normally use 0.002" neck tension. There are so many variables we can work with that we can drive ourselves a bit crazy sometimes, so there are some that I simply standardize. By turning all my necks to the same thickness and using the same size bushing, I can generally count on consistent neck tension. Ideal? Who knows, but it works well for my purposes.

    Old article on the basics of neck tension for newer reloaders: http://riflemansjournal.blogspot.com/2009/10/reloading-neck-tension.html
     
  5. stgw77

    stgw77

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    I use 0,001" or 0,002" for bechrest rifle and 0,003" to 0,005" for semi autos.
    Have bushings in 4 sizes for one caliber and try all of them and use than that one which gives me best ES/SD and accuraccy.
     
  6. 1shot

    1shot Site $$ Sponsor

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    I will try to answer this by starting with the following statement. I turn all my necks like German does for the same reason he does. I will normally run .002-.0025 neck tension, but if I notice the ES numbers to be on the high side, I'll increase it by .0005 to.001 and things tend to settle down. I attribute this to the slow powders that I use, and believe it allows the bullet to stay in place a nano second longer while the powder lights up. I'm sure my theory is full of holes, but it works for me.
    I hope this helps,
    Lloyd
     
  7. Preacher

    Preacher Silver $$ Contributor

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    GLO-- I think you have this backwards---
    (An annealed case neck has very little spring back and a hard worked neck as a lot of spring back)
    Work hardened brass has very little spring back if any at all, how can it ??????
     
  8. wapiti25

    wapiti25

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    preacher, re-read the post by GLO as he did have it right. annealed brass is soft. working makes brass hard, just like bending a piece of copper wire multiple times it will break.
     
  9. Cheechako

    Cheechako

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    Just my own ignorant opinion, but I don't think the amount of tension (.002", .004", etc) makes a whit of difference. All of the comments about "what works best for me" are anecdotal at best.

    What really matters is UNIFORMITY of tension.

    See my article on Stepped Neck Cases.

    http://www.6mmbr.com/compcartridges.html

    Ray
     
  10. BoydAllen

    BoydAllen Gold $$ Contributor

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    Ray,
    How many truly scientific double blind studies have you seen in the shooting sports? Saying that others information is anecdotal implies that yours is not...right? I have known shooter that do well with little neck tension, and those that did as well with a lot. IMO your point about uniformity is right on.
    Boyd
     
  11. Cheechako

    Cheechako

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    Boyd

    I always say, "Do not listen to what others tell you, especially me. I could be wrong."

    The only true double blind studies that I'm aware of are the tests done by Sierra re: moly coated bullets. They were done back in the 20th Century. And yet, shooters today still use coated bullets, based mostly on anecdotal evidence. ::)

    Ray
     
  12. BoydAllen

    BoydAllen Gold $$ Contributor

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    The need for neck tension is pretty much powder related, at least in the 6PPC.

    A couple of shooters that I know, that are much better than I (long list) use about all of the neck tension that one can manage with short range Benchrest bullet weights and 133. When I learned of this, i was using less. When I increased my neck tension, my groups became more consistent.

    I think that 133 "likes" a quick initial pressure rise to do its best work.

    On the other hand, I had some old 2015 that shot very well with almost none. Thinking that I was onto something, I bought an 8 lb. jug of current production. It was not the same. A friend got a very good deal. He uses it for another caliber, with a lighter load, and it does fine. I let him test it.

    It is my belief that when using bullets of higher sectional density, that the bullet's inertia is enough to furnish sufficient pressure rise to insure a consistent burn, but I lack enough data to make this more than a guess.

    Getting back to 133 and the PPC, I have seen an article that pointed out that at the amount of neck tension (difference between sized necks and their measurement over the bullets pressure ring after seating), that I use, that there is no increase in bullet pull over a lesser value. What the author may not have considered is that for a bullet powder combination that shoots best with the bullet a long way into the rifling, that the lager step in the neck at the base of a flat base bullet, may increase its resistance to being pushed back in the case neck as the round is chambered, and that this would create a longer jam measurement.

    Again, this is only my experience with one powder and type of bullet, in one caliber. With a different combination, I would start from scratch, and let the rifle tell me what it likes.

    Boyd
     
  13. Forum Boss

    Forum Boss Administrator

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    Re: Neck Tension -- The amount of tension is more complicated than some realize

    There is no "best" -- some guns/cartridges work well with .001 neck tension, some others need more... maybe a lot more.

    But here's a suggestion that may help put things in perspective. Think in terms of overall bullet "grip" instead of just bushing size.

    Bullet grip is affected by many things, such as

    1. Neck-wall thickness
    2. Amount of bearing surface (shank) in the neck
    3. Surface condition inside of neck (carbon can act as a lubricant; ultrasonic cleaning makes necks "grabby")
    4. The springiness of the brass (which is related to degree of work-hardening; # of firings; time between annealings)
    5. Time during which the loaded round has sat prior to firing
    --and there are others...

    You can do this simple experiment. Seat a boattail bullet in your sized neck with .150" of bearing surface (shank) in the neck. Now remove the bullet with an impact hammer. Next, take another identical bullet and seat it with .300" of bearing surface in another sized case (same nominal tension). You'll find the deeper-seated bullet is gripped much harder.

    I have also found that thinner necks, particularly the very thin necks used by short-range benchresters, require more sizing to give equivalent "grip". Again, do your own experiment. Seat a bullet in a case turned to .008 neckwall thickness and sized down .003. Now compare that to a case with .014 neckwall thickness and sized down .001. You may find that the bullet in the thin necks actually pulls out easier, though it supposedly has more "neck tension" based on bushing size.

    This use of the term "neck tension" when we are really only describing the amount of neck diameter reduction with a die/bushing is really kind of inaccurate.

    We don't have any easy way to measure "true" neck tension on a bullet.

    My point here is that it is overly simplistic to ask, should I load with .001" tension or .003". In reality, an .001" reduction on a thick neck might provide as much or MORE "grip" on a long bullet than an .003" reduction on a very thin-walled case on a short shank.

    What I think this means... and this is only a theory... is that I suspect the guys using .001" "tension" on no-turn brass may be a lot closer to the guys using .003" "tension" on turned necks than either group may realize.

    This doesn't really provide any answers. You have to go out and test empirically to see what works, in YOUR rifle, with YOUR bullets and powder. And you may have to change the nominal tension setting (i.e. bushing size) as your brass work-hardens or IF YOU CHANGE SEATING DEPTHS.

    All I'm saying is that the nominal bushing size is not really a satisfactory indicator of the true amount of neck grip on a bullet, or the force required for release. TRUE GRIP (;D) is a much more complicated phenomenon, one that is affected by numerous factors, some of which are very hard to quantify.
     
  14. BoydAllen

    BoydAllen Gold $$ Contributor

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    Good points all. I should mention that the rifle that I wrote of has a .262 neck.
     
  15. Preacher

    Preacher Silver $$ Contributor

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    wapiti25---I did reread it and I still don't think that work hardened brass will have very much spring back to it.. I always figured the reason to anneal brass was to put it back into a soft state so it would again spring back after it was fired..
     
  16. spclark

    spclark Gold $$ Contributor

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    I started annealing cases after noticing that some sized necks in a processed batch didn't have the same inside diameter as others, despite having been sized using the same bushing and die settings. Taking it a step farther I began measuring shoulder set-back too & found the same thing to be true.

    I inferred from this that each case, having experienced work-hardening from repeated sizings & firings, was behaving differently from others in the same batch because of the difference in "spring-back" or metal memory. Once I started annealing cases I found sized case dimensions became more uniform.

    To me, work-hardened brass exhibits more "spring-back" than annealed and inconsistent as well from case to case. Annealing makes brass response to sizing more uniform; it still exhibits metal memory but to a lesser and more uniform degree.
     
  17. Ackman

    Ackman

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    Re: Neck Tension -- The amount of tension is more complicated than some realize

    This is the best answer I've seen about neck tension.
     
  18. Cheechako

    Cheechako

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    Can anyone give me a number - how many firings of a case does it take before it is no longer acceptable and needs to be annealed?

    Set your own criteria as to caliber, pressure, neck or FL size, etc, etc.

    I just need a number. Any number. Anyone?

    Ray
     
  19. BoydAllen

    BoydAllen Gold $$ Contributor

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    Preacher,
    As brass becomes more work hardened, it also has more spring back. The best example of this is that one has to reset the FL die, closer to the shell holder to get the same shoulder bump. If you leave the die as it was adjusted for new brass and switch to work hardened brass, the shoulder will not be bumped, and the reverse is true. If leave your die as it was set for work hardened brass, and use it to size new brass, you will get more bump than you wanted.
    Boyd
     
  20. GermanS1

    GermanS1

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    Ray, I wonder the same thing. Having never re-annealed a case, maybe I'm missing out and don't know it. My take on it is that re-annealing is of some benefit after cold-working the neck enough to make it hard and brittle and prone to cracking.

    How many firing/sizing cycles it takes to get there would depend to a large extent on how much you're working the neck - i.e. how much chamber neck clearance is there and how much do you (over) size the neck? With small clearance, say 0.002" and using a die that just brings the neck back down to where you want it, I've never had a neck split with up to 30 firings on some 6BR brass.

    On the other hand, if there is a lot of chamber neck clearance, for instance a 0.345" chamber neck in a .308 using Winchester brass which measures 0.333" loaded, and let's say you use a conventional die that sized down to 0.328" and pops it back to 0.331" with an expander, well, I wouldn't expect the brass to go too many cycles before the necks split. Re-annealing might be useful in that kind of situation.

    Because my rifles are set up like the first example (close neck clearance) and I size the necks just enough, this hasn't become an area of concern for me.
     

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