Bumping the shoulder on .223 and the case growing?

Discussion in 'Handloading and Reloading' started by 71GTO, Apr 7, 2021.

  1. 71GTO

    71GTO Member

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    I have been reading almost every post on this forum to gain a better understanding of bumping the shoulder back on my fired 223 cases, which are fired from my Axis II. The new Lapua cases come out of my chamber at 1.452" as measured with a Hornady comparator. I set up my Lee FL sizing die to bump the shoulder .002" and after putting them in the comparator again they measure 1.450" so it appears that the shoulder is indeed moving .002". The problem is however that the case is also stretching from 1.751" OAL to 1.754" OAL after coming out of the die. After reading so many posts on the subject, I thought that one of the reasons for only bumping the shoulder .002" was so that you wouldn't have to trim the case so often, but a .003" gain in OAL seems excessive. Am I doing something wrong or is it normal to get .003" or more of stretching when bump sizing with a FL sizing die? Thank you all.
     
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  2. WVRJ

    WVRJ Member

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    You won't have to trim as often,but you will have to trim.Cases that are once fired almost always need trimming,they're usually longer than the max length by a few thousandths.You bumped the shoulder but the brass tends to flow up into the neck.Growing .003 after sizing is nothing to worry about.Trim when they reach 1.760 OAL and you'll be fine.
     
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  3. Bfh_auto

    Bfh_auto Member

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    They grow more the first firing or two. Then it settles down. I trim every time anyway.
     
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  4. AJC1

    AJC1 Member

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    Growth has a lot to do with chamber vs die size. A generous chamber and a small die means maximum growth
     
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  5. edwardware

    edwardware Member

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    @AJC1 is right. To expand on his point: you imagine that bumping the shoulder 0.002" is small, but you aren't measuring body diameters at all. If your chamber is a bit larger in the body than your die, your 0.002" bump could be pretty significant.

    On the whole. 0.003" growth per firing is quite small. Trim every 3 firings, and go shoot.
     
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  6. Walkalong

    Walkalong Moderator Staff Member

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    Squeeze cases in to size them and they get longer. Has nothing to do with shoulder position.
     
  7. Trent

    Trent Member

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    100% this.

    Primary failure mode on bottleneck rifle cases is case failure at the webbing (case head separation), as brass flows under pressure while fired, and again is squished when sizing. What you are seeing as growth is the brass being forced against the chamber under tremendous pressures. Eventually, after enough firings and sizing, this leaves the brass around the case head thinner. What was previously material in the shoulder is in the neck, what was previously material in the body is now shoulder, etc. The material you remove while trimming has to come from somewhere. :)

    Another failure mode is shoulder separation, if you have a loose chamber and you are constantly having to push the shoulder back, it can create a weak spot at the shoulder/body junction and then you have to break out the handy-dandy broken shell extractor tool to pull out the shoulder and neck, when the rest of the body is ejected.

    Personally, I *do not* attempt to push the shoulder back whenever possible. I match bolt action brass to that rifle, and that is paired for life. I only neck size from that point on. I can get *many* neck sizings out of that brass, as there is never a need to bump the shoulder back, sometimes 10 or more, before there's any sign of failure, and I don't have to trim as often. When it comes time to need a third trimming, it's recycled.

    For 5.56 where I don't know what rifle it'll get shot in, I use a SAAMI small base sizing die to ensure it'll work in all of my rifles without issue, since it's random luck when that cartridge gets put in to what rifle. This works the brass far more than neck sizing and does come at the cost of that recycling point of the brass happening much quicker. But this is because each time I'm resetting the case back to original SAAMI specs, and not just neck sizing.

    If you are shooting *that* ammo in *that* rifle, there's not a compelling reason to ever so much as touch the shoulder. I have had cases go through 8 or 10 or more firings in bottleneck rifle (through that same gun) without once touching the shoulder during the resizing process. That is due to that brass being fireformed to that specific chamber; it greatly extends the lifespan of that brass.

    For semi-autos, though, you do want to at least full length size or (if you have multiple rifles) pick up a small base die to get them clear back to original SAAMI specs. Cases won't last as long but reliability is a bigger concern!
     
  8. Trent

    Trent Member

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    Also keep in mind CUP pressure listed in reloading books is a copper crush test. The chamber (and casing) have a hole in them which is aligned and a copper plug is inserted. CUP pressure is how much that copper plug is crushed by the chamber pressure.

    Brass is also crushed every time you fire; it just smooshes forward, as it has nowhere else to expand to. :)

    A little easier to think of, when you think of it more of a liquid than a solid.
     
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  9. 71GTO

    71GTO Member

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    Trent, after reading so many posts on this subject there appears to be two separate camps on neck sizing only versus FL sizing and bumping the shoulder for bolt guns. I just recently got a new Savage II in 223 as all of my other rifles that I reload for are either AR10's or AR15's. I've shot about 200-rounds of my reloaded new Lapua brass through the Axis so it was time to start processing them to reload a 2'nd time. I guess I chose to resize and just bump the neck .002" because it seemed that more people (by just a small margin) were pointing in that direction versus neck resizing. Luckily I also have a Lee Collet necksizing die as well so I could just neck size and now that I see how much my good brass has lengthened after putting it in the FL sizing die and reading your reply I think I am going to change direction and try just neck sizing the remaining 175 cases I have. After firing my 200 new Lapua brass in the axis and measuring the case headspace prior to shooting them, I'm pretty sure my chamber size is 1.452" as measured with the Hornady comparator even though I realize that this is not the exact measurement since the comparator doesn't have that ability, but it gives me a number that I can use. Is there anything special in addition to just sizing the neck other than my regular prep that I will need to do? Other than how the bolt opens and closes, is there any other check to make on the fired brass after just neck sizing? Sorry for the questions, but I appreciate your advice. Tom
     
  10. 243winxb

    243winxb Member

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    If fired brass will go back in the chamber, after firing, then neck sized brass should also. Dont buldge the shoulder when neck sizing. https://support.leeprecision.net/en/knowledgebase Tips on how the Collet Neck die works, from Lee.

    The neck tension/bullet hold has to be checked, till the learning curve is reached.
     
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  11. AK Hunter

    AK Hunter Member

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    I was neck sizing some 6.5 Creedmoor cases for use in my bolt gun but found them getting longer after every shot. I finally had to go back to full length sizing & trimming to keep the length right so the bolt would close.
     
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  12. South Prairie Jim

    South Prairie Jim Member

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    When I used a die with the expander ball system my brass always grew more than just using a FL bushing type die.
    Thinned out my necks also, kind of a pie dough effect. I picture it being a violent process.
     
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  13. NMexJim

    NMexJim Member

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    If I've got it right, the Axis II is a Savage bolt gun. By only setting the shoulder back .002, you're keeping the cartridge case as close to that rifle's chamber size, and thereby maximizing benefits such as concentricity and headspace as much you can and not have feeding problems.

    Small-base dies will size back to minimum SAAMI case specification, and that will decrease case life from overworking. But, if you're going to fire the loaded rounds in more than one rifle especially semi-auto, then just F/L size.
     
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  14. 243winxb

    243winxb Member

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    To avoid less working of the neck, i recommend using a FL sizing bushing die, like a Redding Type S.
    To get maximum case life out of any brand of 5.56/ 223 brass.
    A Lee collet neck sizing die, should also reduce over working the brass. Over worked brass gets brittle & cracks, if not annealed.

    Outside neck turning is another way to avoid over working 223 bolt brass. I turn and use standard RCBS dies.

    The thick brass area, right at the neck shoulder junction, may seem to make it almost impossible to pull an expander out of the case when FL sizing, even with lube. (Standard dies)

    Normalapua.jpg 702206-addf8673a722567433bd6684eb4c9e9d.jpg SavageAxis223R.jpg
     
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  15. Trent

    Trent Member

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    If you are only firing *those* casings in *that* rifle, you really don't ever need to move the shoulder, or size the body.

    In the old days I'd just back off the normal full length sizing die so that I was only sizing about 3/4 of the neck; the body didn't get touched, and the shoulder never got touched. Poor man's neck sizer.

    These days I use (on precision rifle) competition bushing dies that complement my chosen neck turn and desired throat diameter, but those cost a pretty penny and brass prep is a much slower process with the extra stages. You can do just fine with a neck sizing die.

    The only time I ever full length size is on ammunition that is fed through semi-autos. In a handful of calibers I use SAAMI small base dies, depending on what it was shot in last, and what it might get shot in next (if I have a clue, usually I don't). Some of my guns are looser than other, in specs, and full length sizing isn't enough to get the brass fired in them back to spec for "the rest of the rifles" in that caliber :)

    Anyway backing this off to the simplest form; in a bolt action there's really no reason you'd ever need to touch the shoulder, if that's the only rifle that brass will be used in, since the case is fireformed to the chamber, the chamber is generally very well (fully) supported, and so on. For bolt actions, neck sizing is enough, and there's a lot of die options for that.

    If you have more than one rifle in that caliber, headspacing and chamber support / dimensions may be quite different between them, so you'd want to full length size. This will work the brass more, and it won't last as many reloads.

    Small base (SAAMI) dies are a last resort if you want to reuse brass in a gun that has a loose chamber or other characteristics that mess with brass. H&K fluted chambers are notorious for this, when I shoot brass out of a fluted chamber gun, it is almost certainly going to get a small base sizing die before I put it back in to general circulation. :)

    Generally speaking I match all bolt action rifles to the brass for that rifle; and if I have multiples of a caliber I keep it separated. To make this process cleaner in some calibers where there's several bolt actions I'll separate it out by brand. E.g. in 308, I have Nosler, Lapua, Remington, and Winchester brass (all purchased new) which couple a particular bolt action in that caliber, that way I have another safeguard against mixing them up.
     
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  16. Trent

    Trent Member

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    You still need to trim if you neck size. That brass flows under extreme pressure while firing; it doesn't just grow from sizing! Full length sizing moves more material around and they will appear to "grow" faster; but whether you neck size, or full length size, it's the act of firing that case that makes the brass flow like a liquid under tens of thousands of PSI under incredibly high temps.

    I use go/no go drop gauges w/ max cartridge length for every caliber I own so I can quickly sort out when things need a trimming. After I finish sizing, I run a random assortment through the drop gauges; if any don't clear, the entire batch gets trimmed.

    Can't remember who I had make those, had them a long time. Was a guy I think on THR I ordered them from, he made them to your exact spec on a laser cut table. All were made to my spec; on most calibers I had them made 0.001-0.002 under the max; except for 50BMG, I think I had that under cut by a larger margin, since there's a hell of a lot more brass that flows on them. :)
     
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  17. 243winxb

    243winxb Member

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    I dont agree with this. Sorry.

    At normal maximum pressures, soon or later brass will have to be full length resized for a bolt action. But hard closing of a bolt action will push the shoulder back on 223 brass. In fact, an M16A1 will set the brass shoulder back, when the bolt slams home on a sized brass that has a to long head to datum measurement for that chamber.

    My 223 Axis firing pin strike will set the shoulder back as much as .006" head to datum. Found this out with a bad CCI 400 primer. (Wrong primer for 223)

    As always, do your own testing to know. As always, imo.
     
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  18. Trent

    Trent Member

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    Well, as usual with reloading, experiences may vary.

    But I have several calibers in several rifles which I've shot to 10, 15, 20+ times (after annealing) which I never purchased full length sizing dies for, which have only had the neck touched.

    The brass case springs back after firing; if it didn't, you wouldn't be able to extract the round.

    So there's nothing mechanical about a bolt action that would cause a case to stretch beyond the chamber dimensions, as far as the shoulder is concerned, due to spring back.

    If you see this happen on max loads, it's just about certain to be the web that is expanding, not allowing it to clear, and not the shoulder. In the *web* is expanding, you're shooting too hot of a load to begin with, or your headspacing is too loose.
     
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  19. NMexJim

    NMexJim Member

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    71GTO - be sure and note “annealing” in Trent’s post. If you have no experience w/ annealing, search it.
     
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  20. South Prairie Jim

    South Prairie Jim Member

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    After a few firings my brass develops semi hard bolt closeure ( is that a word?) if I continue and fire that round i will develop clickers when I open the bolt.
    How can I avoid that by just neck sizing?
     
    Last edited: Apr 7, 2021
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  21. Walkalong

    Walkalong Moderator Staff Member

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    With proper sizing of bottle necked rifle cases being fired at under SAMMI max pressures you should never have case head separations. You should lose the brass from split necks or loose primer pockets.

    Once fired brass will still chamber freely, so if you keep the shoulder in that position, or move it .001 or .002 back from there, you'll be fine.

    If you really want to know max chamber size, it takes more than one firing on new brass to come out nearly filling the chamber.

    A thread about case head separation.
     
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  22. Walkalong

    Walkalong Moderator Staff Member

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    You can't, you either supplement neck sizing with a body die, which I have never understood, or you FL size with a standard sizer, or use a bushing style FL sizer. The latter is the preferred choice for straight cases and accuracy. Either that or a FL sizer with the neck honed out to match your brass.
     
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  23. 71GTO

    71GTO Member

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    Walkalong, That is what I have always heard regarding taking more than one firing to fill the chamber with new brass. In my case with new Lapua brass fired one time, would you recommend bumping the shoulder .002 or neck sizing only (or does it matter) for the next couple firings to get a true size of the chamber? Thank you
     
  24. Walkalong

    Walkalong Moderator Staff Member

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    You can neck size a couple of times, firing full power loads, and in three or four firings you can figure that's as long as the base to shoulder is going to get. I used to do similarly, but now I just move the shoulder .001 or .002 after the first firing, keeping an eye on the fired shoulder position after that.

    For my 6 Dasher I logged the fire formed shoulder position, the sized shoulder position for the next firing, then that fired shoulder position, and continue. If I see that I need to adjust the sizer up a hair and size less, I would, but I did not. I don't get that carried away for most stuff though.

    I size .223 cases for the AR to fit a Wilson headspace gauge, and I still get 8 to 12 firings on cases, with no signs of incipient case head separation, before I lose the cases to loose primer pockets (usually), or a split neck (sometimes).
     
  25. NMexJim

    NMexJim Member

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    what’s a “clickers”? I’ve never heard that term before.

    Walkalong said it. You can neck size a few times and then it’s going to be time to F/L time and you might as well anneal then too. My .243 had best not be pushed out past three hot firings with just neck sizing or I’m in trouble with bolt lift. I just quit neck sizing altogether because it’s hard for me to guess-ta-mate, and so I only shoulder bump now. I have not had the same issues with 5.56. Pretty much same, same as Walk.
     
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