Neck- vs. Full-Length Resizing

Discussion in 'Reloading Forum (All Calibers)' started by South Pender, Jun 19, 2017.

  1. South Pender

    South Pender

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    I have to acknowledge that I haven't been following recent thinking regarding resizing, but I get the impression, from this and other forums, that the current view is that full-length resizing may result in more accurate ammunition than neck sizing.

    I've just returned to reloading after a few years in the rimfire world, and I had thought that by neck sizing, you were allowing the case to conform better to the rifle's chamber, keeping it better centered, with better accuracy the result. (This is assuming, of course, that the reloaded round will chamber without problems.) In the past, I have generally used Wilson chamber-type dies that leave some of the neck just ahead of the shoulder expanded, and the loaded rounds have been a nice fit to the chamber while still chambering with ease. My thinking has been that unless loading really hot rounds, this process should allow a number of reloadings before the need to FL resize and start over again.

    So is this no longer the prevalent thinking in reloading circles? For context, I've just started reloading again with a Sako 6 PPC. Is there a better way to prepare my cases than my old practice?

    Thanks in advance for your insights on this....
     
  2. Bart B.

    Bart B.

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    Sierra Bullets proved in the 1950's that proper full length sizing of bottleneck cases produced best accuracy when their ballistic tech tried every fired case sizing tool and setup known to man. 30 to 40 reloads per 308 Win and 30-06 cases were then normal. Some folks got 50 to 60 even with max loads.

    Most of the benchrest crowd finally started that some 15 years ago. Their smallest groups stayed the same size. Biggest ones got smaller.

    Single piece full length sizing dies keep everything in alignment when fired cases are sized down a couple thousandths. Neck only dies don't do that. Cases don't rest in the chamber bottom when fired; they're pushed forward into the chamber shoulder centering them perfectly regardless of case body diameter. Firing pins do that. None of the body touches the chamber walls except the back end at the pressure ring pushed there by extractors pushing them.

    I've always got better accuracy with new cases compared to neck only sized ones. They center bullets very well in chambers when fired.
     
  3. SheepDog

    SheepDog Silver $$ Contributor

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    This is a question that depends on the sizing die you use and the chamber it is fired in. I have a gun that has a chamber that is very large in diameter. If I full length size with an "off the shelf" sizing die it will rupture cases in as few as three reloads. I have never had new factory ammo produce better than two inch groups in that rifle. It would be considered worn out by most shooters but by only partially neck sizing, a process that doesn't resize the body of the case at all, using a neck sizing die I shoot reloads to under 1" at 100 yards. Contrary to popular belief I have never had to full length resize due to cases becoming oversize from repeated firing. I don't load "hot loads" because I am a hunter who limits shots to 200 yards and I don't need the added velocity. So 45 years of my experience shows that the best way to get accuracy from that rifle is to only partially resize the neck.
    If I had a custom rifle with custom dies then using the full length sizing might be better especially if I was pushing loads in excess of maximum pressures to keep a bullet above the transonic region of velocity at 1000 yards.

    It comes down to the combination of rifle, die, and the loaders need. There will never be one answer for all the reloaders in the world. That is what makes reloading so great. You try different things, one at a time, to find out what works for you in your rifle under your conditions. You keep what is successful for you and throw the rest away. Never be afraid to try something that nobody else is doing because it might work for you in your gun.
     
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  4. South Pender

    South Pender

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    Thanks, Bart and SheepDog. Bart, you've included stuff I didn't know--like FL-sized or new cases staying centered in the chamber. I had always thought that they rested on the bottom of the chamber. It sounds as though careful FL sizing should introduce less runout in the cases than neck-only sizing.

    I've gone to the Sinclair online catalog and see several FL bushing dies. Is there a front-runner in that group? In the past, I've found the L. E. Wilson dies to be topnotch and see that there is an L. E. Wilson FL bushing die.
     
  5. T-shooter

    T-shooter

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    I resize new brass in the hopes it will make all of the cases the same. Even Lapua brass can benefit by this. I've found good and questionable quality in every brand I have tried. I have the full length die set to push the shoulder back no more than .001". The neck I.D. ends up being .002" under the bullet diameter. I did some measurements with a couple F/L dies a few years ago. The Forster benchrest die doesn't overwork the brass. This is the difference of resizing vs a fired case in my rifle. Closer would be better especially near the shoulder but still it's not really overworking the brass like a cheap Lee die.[​IMG]
     
  6. Lucky6547

    Lucky6547

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    If you want, you can take three pieces of brass, fire them 3x each with neck sizing between each shot, and then send the unsized brass after the third shot to Harrell's or Neil Jones or Whidden and have a custom die made for your gun. Then you'll have a die that's closely matched to your chamber...
     
  7. SheepDog

    SheepDog Silver $$ Contributor

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    South Pender,
    You have a chamber with a tapered body, a shoulder and a neck. The cartridge has all those parts too. I often hear about bumping the shoulder back .002" and sizing the case body so it fits loose in the chamber. Gravity is ever-present and unless you load the bullet long enough to center the nose in the rifling and at the same time push against a close fitted bolt how can the cartridge be centered? It has to droop at the back end and it doesn't engage the shoulder what holds it in the center of the chamber? It can't be the neck because there must be at least .002" of slack to expand into in order to release the bullet.

    These are the contradictions I hear when I listen to all the advice from the long range shooters. I have no experience in their sport and it seems to work for them. I have to assume that their dies are made so that minimal sizing is taking place on the body of the case (custom dies fit to their chambers) and that the front of the case is aligned by pushing the bullet into the rifling. Pushing the bullet into the rifling goes against everything I ever learned about reloading. It raises pressure dramatically. As I said, it seems to work under the conditions they work in but as with all reloading advice be cautious in your development.

    I was writing my reply before the above post - this makes sense to me.
     
  8. BoydAllen

    BoydAllen Gold $$ Contributor

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    As with many things, the answer is "It depends". If your loads are always light, you can do a lot neck sizing, but you should pick a number for neck sized firings per case before FL sizing that is less than the number of shots that it takes for ANY of your cases to become tight. This is why. Groups fired with a mixture of tight an un-tight brass will be larger than if they are all tight, or all not tight. Cases do not all get tight on the same firing, even though they have been fired with the same load.

    Years back, a Benchrest Hall of Fame shooter, and record holder that I know, Gary Ocock, used to come to the Visalia, CA matches and size his PPC cases all weekend with a tong tool neck die. I never gave that much thought until recently, when the obvious conclusion finally dawned on me. If he was neck sizing and not struggling with his bolt, he must have been shooting relatively light loads. I suppose that I should add, that many shooters would have been quite happy to have shot as well as he did, and does.

    Time has passed, and he no longer uses the tong tool, but I brought that up to make a point. In short range benchrest, accuracy trumps everything, and if you can read flags with an accurate but slow load, you stand a very good chance of beating folks who are shooting less accurate rifle/load combinations however high their chronograph readings, or for that matter bullets' BCs may be.

    Having said all that, if you have no experience with a die that is fitted to your chamber, your impression of FL sizing is very likely to change once you have one. They hardly move the brass at all, and have the advantage of providing consistent fit for every firing, as long as they are set correctly. I mention this because we do have to adjust them as our brass hardens from being fired multiple times. .001 bump can become .000 with the same brass and setting.

    My final point is this. I encourage you to cast aside the "you would think"or "it seems to me" mentality if favor of actual testing. What I have found over the years is that things do not always work the way that I thought. Test, and believe your targets.
     
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  9. dmoran

    dmoran Gold $$ Contributor

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    While I do agree that pressure does rise, but have never seen it rise "dramatically". In pressure traces, it is common for me to see 0.5 to 1-1/2% rise in pressure from say 010"-Off to 010"-IN, but can't ever remember seeing anything over about 2%, or rises that I would consider "dramatic".
    Even without conducting actual pressure tests, one can make fairly accurate pressure judgement by obtained velocity data and/or POI shifts on the target. Where to get a "dramatic" rise in pressure, you would also need to see dramatic velocity and/or POI shifts as well.
    My 2-cents
    Donovan
     
    Last edited: Jun 19, 2017
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  10. Tiratore

    Tiratore

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    I started in benchrest competition with Wilson neck-only dies. I moved to "near-FL" a few years afterwards to make gun handling easier; after several reloadings, the bolt lift effort increased to where "running" a group was problematic.
     
  11. Richard Coody

    Richard Coody Silver $$ Contributor

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    Man

    I don't understand where this unreasonable fear of jamming bullets comes from. You see it.mentioned in all the shooting forums. Personally i find jamming VLDs makes them extremely accurate. Lots of the reloaders woes disappear like runout and seating depth. Soft seating solves the problem of when to load your ammo. Hell you reseat with your bolt.

    Of.course like anything else in reloading you work up.

    And those that are so fearful of the jam never discuss the pressure rise resulting from deeply seated bullets.
     
  12. Bart B.

    Bart B.

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    They don't stay centered in the chamber. Their shoulder is centered when fired, sometimes when the bolt is closed before firing.

    A few ounce firing pin pushed by a 25 pound rated spring moves about 9 fps when it first touches the primed case. Then it keeps on pushing until the case shoulder stops against the chamber shoulder then centers there. I call that the "2 stacked Dixie cup syndrome."

    Before the trigger is pulled, in line spring loaded ejectors push forward on case heads.

    Extractors often push case heads off center in the chamber; post '64 Win 70 push feed ones push case heads up as they're on the bottom bolt lug.

    I've watched case necks center perfectly in chamber necks from external forces on them. Good education on what really happens.
     
    Last edited: Jun 19, 2017
  13. Shynloco

    Shynloco You can lead a horse to water, but ........ Silver $$ Contributor

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    I have recently become more acutely aware, in part, of what Boyd is referring too. Over the years, I'd been told of the advantages and wisdom of having custom dies made for a particular rifle. But I recently GOT LUCKY (I guess) when I bought a new PTG Match Reamer to chamber a new Kreiger 1:13.5 twist barrel for my .260 Remington. And for the first time in my years of reloading (using a Redding 260 S Die), I discovered that my Lapua brass wasn't growing (after the initial trimming following the first firing) and my shoulders remained the same and didn't need to be bumped, even after five shootings of the brass. And that remains constant even employing what Donovan just referred to with a 2% increase in pressure resulting from (hard) jamming the bullet into the rifling, another something I'd not done before. And the end results was really great groups (@100 yds) using Berger 140's being pushed by RL-19. Finally, I strongly believe in what Boyd closed with when he writes, Test and believe your targets.

    I respect the "Opinion" shooters may have. But even following words of wisdom offered by some really talented shooters and proven Experts, what may works for some folks in their particular rifles, may not always hold true in every rifle being shot, even on a competition line of hugely qualified shooters.

    Alex
     
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  14. SheepDog

    SheepDog Silver $$ Contributor

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    The tests I have seen compared bullets seated at recommended lengths at which loads were worked up for manuals and then gradually seated further forward to the point of contact with the rifling. Some of the loads produced over 30% increase in pressure over the pressures taken at listed OAL. Here is just one such test:
     

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    Last edited: Jun 19, 2017
  15. South Pender

    South Pender

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    SheepDog, that's an interesting piece from Hornady. Here's the full piece:

    http://www.hornady.com/ballistics-resource/internal

    The last three paragraphs describe what happens with the bullet seated to touch the rifling. Further up in the article (about halfway through it), they state:

    "Though some rifles deliver their best groups when full length resized, neck sizing alone usually promotes better accuracy, because when our reloaded cartridge is returned to the chamber it is almost a perfect fit; headspace is just right with all cases, whether rimmed, belted, or rimless; and most helpfully of all, the new bullet is almost perfectly aligned with the bore."

    This is how I had remembered things. However, the helpful comments in this thread have alerted me to the fact that the issue is more complex than I had imagined. I like the idea of a custom-made resizing die--a la Harrell, Neil Jones, or Whidden--although the cost is high.

    One thing that surprised me in reading about these dies on the Whidden website, is that resizing the neck with one of their bushing dies involves an expander button as well, as the last stage of the resizing (from the Whidden website):

    "As the sizer die is removed from the case the bushing exits the case neck and the expander ball returns through the neck. The diameter of the expander ball will determine the neck tension. When this action occurs the inconsistencies of the case neck wall are forced back to the outside of the neck case. In our experience this allows for a more consistent neck tension when the case is loaded."


    I had always thought that a real disadvantage of an expander button was the possibility of pulling the necks out of concentricity. The plot thickens....;)
     
    Last edited: Jun 19, 2017
  16. BoydAllen

    BoydAllen Gold $$ Contributor

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    The manuals that I have read listed something on the order of 5,000-6,000 psi increase when going from seating off the lands to touching or seating into the lands. I am curious, how did you measure the 30% pressure increase that you mentioned? Over the years I have loaded most of my ammo with bullets slightly into the lands, but of course I did my workups with them seated that way. I am about to do a pressure test for a new barrel in a new caliber. This time I am going to try some loads with bullets jumping, so I will load two tests, one with bullets jumped and the other with them into the lands. It will be interesting to see what the difference in max loads will be. In the past I have always done my initial pressure testing with bullets loaded longer than touching as a sort of worst case situation, so that any thing that I loaded shorter (within reason) would always be safe with that maximum charge.
     
    Last edited: Jun 19, 2017
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  17. SheepDog

    SheepDog Silver $$ Contributor

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    Boyd,
    I don't have the equipment necessary to test pressures. The tests that I saw were of actual pressure traces that were taken with a near or maximum load at the recommended OAL and then gradually getting closer to the lands until they touched the lands. The reason it stuck in my memory is that it was actually over the pressures generated by a "proof" cartridge which is generally about 30% over the normal pressures.
    Working the loads up with the bullet in the place you will shoot it is the preferred method as long as you recognize that you can't go all the way to the maximum listed load without getting excessive pressures. You sound like you fully understand what you are doing.
    A quick note on my method of pressure testing. If I cant get a minimum of 10 loads on a case before the primer pocket loosens then I know the pressures are too high. Most of my cases have been loaded well over twenty times and the batch I loaded last night have now been reloaded 43 times with only partial neck sizing. It seems to work in that gun, a 3006 03A3 issued in 1942. :)
     
  18. HTSmith

    HTSmith

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    140's in a 13.5" twist? I must not be reading it right.
     
  19. Bart B.

    Bart B.

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    Redding may be the best bushing die. Maybe RCBS. I think the best commercial full length dies today are Forster's they've honed out necks to customer specs for $12 extra.

    As far as I know, Sierra Bullets now uses Redding full bushing dies to size unprepped cases used to test their stuff for accuracy at 200 yards indoors. Their test barrels have virtual SAAMI spec chambers and there's ample clearance from case to chamber. Their match bullets have to shoot 10-shot groups under 1/2 MOA, dozens of groups are shot in a production run of a few or more thousand bullets. Their best lots of smaller calibers will group well under 3/8 MOA one after another after another. They're tested in rail guns so there's no human error involved.

    I've seen sets of their test targets at their California plant with 30 caliber 168 HPMK's all under 2/10ths (some under 1/10th) inch shot in their 100-yard range. Back then, their dies were standard full length ones with no expander balls but necks honed out to .001" to .002" smaller than ammo's neck diameter.
     
    Last edited: Jun 19, 2017
  20. ireload2

    ireload2

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    You can't really draw general conclusions about all dies based on 2 dies. Try measuring 100 FL dies including 4 or 5 of the same brand. There is usually about .002 difference in dies from the same manufacturer.
    The dimensions of the Forster dies do not vary much from RCBS dies or Redding dies and in some cases the Forster dies are tighter.
    The same goes for the head to shoulder dimensions. I have measured many RCBS dies and they seem to target half way between the go and no go gage lengths for their dies.

    I am not a fan of Lee dies but those I have measured usually are very close to the major quality brands. However I have a Lee FL in 7.65 Mauser that is .010 too long in the body so it will not properly size a case. The Lee dies for the 7.5X54 French MAS are about .006 to .008 too small in the body causing the case length to grow rapidly from the excessive expansion and sizing.


     

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