Achieving maximum case life 101

Discussion in 'Ammunition & Reloading' started by Humpy, Apr 10, 2019.

  1. Humpy

    Humpy Member

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    Achieving maximum case life 101
    The dimension of the chamber and the dimension of your dies has everything to do with case life.
    Let's take a look at 308 Winchester. Pull up and print the below for reference.

    http://www.saami.org/pubresources/cc...Winchester.pdf

    Particularly notice the tolerances allowed on cases and chambers.
    Notice there is a datum line .200” up from case rim calling for .4703 and the tolerance is minus .008” which means a factory case can be manufactured from .4623 to .4703 and still be in tolerance.

    In actual practice I don’t think you will find any new 308 commercial cases smaller than .465” and I believe one will find all LC Match unfired cases to be .468”.

    Now look at the chamber drawing at bottom at which calls for .4714 + .002 so a SAAMI chamber can run .4714”-.4734” at that datum and I have seen rifles that give birth to cases that measure .475” ! ! ! ! !

    Best scenario here is obviously a LC Match case at .468 being fired in a chamber that is .4714 so you have an expansion of .0034”. Worst case is a commercial case at .465 fired in a chamber of .4734” or worse.

    Now, look at case neck variations you can get with such chambers. .3442 +.002 is authorized for the chamber and the loaded round neck at .3435-.008” so you can have .3355 case neck and a .3462 chamber neck.

    In ammo, I have measured LC Match M118 that runs .338 on the neck and commercial ammo is a tad smaller and varies but I have found nothing larger than .338 on commercial ammo but then again there are so many and I don’t buy factory loaded ammo to hunt with.


    It is well known the more a case expands from fired dimension the more the brass is “worked” taking it back to what FL dies produce. That brings up other problems. .308 dies I have size .4680-.469 and I have one that FL sizes at .471” as I don’t want to “work” the brass any more than I have to.

    I see hundreds of references to small base dies which beg the question if all 308 dies size base dimension to .468-.469 and the smallest chamber base (fired case) dimension is .4714” how much smaller do you need? I don’t own an SB die and never have.

    Thus, what is one to do to obtain maximum case life? Bear in mind I am talking bolt gun chambers here and not parking lot (M14/M1A) chambers. I have 308 reamers that give me a base dimension of .4685-.469”. Thusly, commercial cases only expand .004” and LC Match expands .0005" or .001" so when it comes out, my fired cases run around .4683” which means the brass has not visibly moved but can be measured. When it is sized, the base does not move. Thusly, the brass more or less retains its factory dimensions.

    I have reamers that cut four neck dimensions: .337, .339, .344 and a SAAMI spec reamer. Rifles chambered with .337” reamer will just chamber Winchester cases with 168 Sierras. Rifles chambered with .339” neck dim reamer will just chamber LC Match and all the commercial I have found.

    Next to be considered is the distance between the case head and the case shoulder.

    Look at the chamber drawing and you will find 1.630 +. 010” range. GO Gages (min) are .1630 and NO GO are normally .1.636 and FIELD SERVICE is 1.640” Thusly on a new factory rifle you will normally see 1.632 - .1.634 and I have seen new factory rifles close on 1.636 NO-GO Gage.

    OK get out your MOTION SICKNESS BAGS and look at headspace dimensions for ammo is .1.634 -.007” so you can have max forward movement of the shoulder go form .1.627 to 1.636 or .0066” range.

    Again talking bolt gun here and not parking lots. I headspace my rifles to give me a fired case of 1.631–1.632" so when I FL size I can adjust my die to give me a loaded length of 1.630–1.631", which means the shoulder is barely moved. I call this the 222 Rule, which means the case moves no more than .002” at base, neck or headspace.

    Now, what does this give me for case life? Well in 308 using LC Match brass I have run tests where I did nothing to the cases and got 90 to 100 loadings. On commercial cases, I discard Federal at third firing and Winchester at 6 to 10 firings when the primer pockets get loosened as I don’t want to cut my bolt faces with the plasma jet-like leakage around the edge of the primers.

    On 30.06 I run .467 base dimensions and .469 on another and I have one 30.06 LC Match case I have loaded 157 times and still waiting for more. ALL 30.06 ammo I have ever measured new unfired is .465” at the base. Based on this and the feel of the primer pocket on this case I can get maybe 20 loadings and then I will move to Wolf Primers which are a tad larger than ours and will snug up the “feel” when seating.
    Based upon the cost of 500 new cases these days, this will pay for one to buy a custom reamer for bolt guns that give tighter dimensions and longer case life and if you like to shoot the reamer pays for itself quickly and it is good for many chambers especially if you use a rougher first.

    Ray Steele who built all the US Secret Service sniper rifles and the match-winning rifles they used for many years is the one that got me on the above chambers about 30 years ago and I bought my reamers from the same place he got his to his drawings and as well his personal reamers. Ray passed a couple years back and I miss him greatly. He was not only a top-flight rifle smith but a former member of US Palma, Dewar and Pershing Teams and to my knowledge only two people have been on all three, the other being Larry Moore. Prior to going to the Secret Service, Ray built all the ammunition test rifles at Frankford Arsenal. He designed the reamer used to chamber the rifle that holds the 1000 Yard Any Sight record and as of this writing is still listed on NRA website.

    I have a reamer made to Ray’s drawing for the 300 Win mag which has tolerances to give max case life as well.

    OK, I fully realize a tight neck can lead to high pressures and the way to make sure all your loaded ammo will fit in such chambers is you take a piece of barrel the same caliber you are shooting or the muzzle section that is normally cut off a blank and run your custom min dimension reamer in the chamber end until the shoulder is cut about .100" and stop. Next, reverse the barrel stub in the lathe and trim it back until you see the end of the case neck and leave the shoulder. This will give you exact information on where your neck is in relation to overall length. The gage is left in the die box and I gage every round loaded to make absolutely sure no interference fit is going in and have never had a case that would not go in my NECK GO GAGEs.

    Bottom line is I have one set of 500 30.06 LC MATCH brass that I have been running since 1982 and they are on their third barrel and all were cut with same reamer I got from Ray Steele.
     
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  2. Hookeye

    Hookeye Well-Known Member

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    I neck size and don't worry about it.
    Keep my cases sorted by rifle.

    Gas to and from the range/hunting fields costs way more than cases.
     
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  3. Humpy

    Humpy Member

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    I do the almost the same thing, keep cases segregated by rifle. That is where my 222 Designs originate from.
     
  4. SGWGunsmith

    SGWGunsmith Well-Known Member Supporter

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    Maximum case life 102:

    I find that the BEST method used to extend case life is to only drink ONE bottle of Dos Equis at dinner. That way 24 bottles will last 24 days. :p
     
  5. Hookeye

    Hookeye Well-Known Member

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    Double Crooked Tree made only in the month of Feb, costs 150 bucks a case.
    I managed to save a 6 pack for 1.5 yrs. Hops dumb down over time. Didn't make it to 2 yrs like prev.
     
  6. locutus

    locutus Well-Known Member Supporter

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    All valid points. All are a good idea for very rare and expensive cases or those laboriously reformed form other calibres.

    OTOH, 99 percent of cases are so inexpensive that I buy by the thousand and don't much worry about it.:)
     
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  7. SGWGunsmith

    SGWGunsmith Well-Known Member Supporter

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    Very true. And even with neck sizing ONLY, primer pockets do wear out, and will enlarge over time and repetitive primer seating.
    Maybe the secret is "Gorilla Glue" in the primer pockets?
     
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  8. Hookeye

    Hookeye Well-Known Member

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    Im not concerned w standard stuff. Might be a little honked off with losing 256 win cases. But they reportedly have a short life span anyway. When i get a tc custom shop rifle bbl ill worry about it.
     
  9. Hookeye

    Hookeye Well-Known Member

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    Maybe im missing something.....but if one is worried about case life.....why full length size? The small base dies mentioned prev......i thoughf that was for autoloaders. Nobody i i know runs em in non autoloaders.
     
  10. Hookeye

    Hookeye Well-Known Member

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    I get more case volume neck sizing. Not a bad thing when using case filling propellants.
     
  11. Gatoragn

    Gatoragn Well-Known Member Supporter

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    Buy a 30 pack. :D
     
  12. Humpy

    Humpy Member

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    I had a good contact at East Alton and he told me their cases would hold up for 5-7 loads.
    My LC Match 7.62 has been reloaded upwards of 90 times. I have a LC Match 30.06 case that has been loaded 157 times and primer pocket is still snug.

    Neither of the above has neck splits as I stress relieve every three shots.
     
  13. alsaqr

    alsaqr Well-Known Member Supporter

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    Humpy, thanks for a great post.

    Except for some rare calibers i seldom re-loaded with case life in mind.

    When it comes to a supply of cases i'm lucky. Most of the re-loads i shoot are .233/5.56mm, .308/7.62mm and .30-06. Most cases are re-loaded a maximum of 3-5 times and discarded. When more cases are needed i contact a friend who owns a public shooting range or shoot some of my military ammo.
     
  14. Humpy

    Humpy Member

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    Alsaqr, Yes I make about every other thing I own from 223/7.62 or 30.06 brass. I make one thing from 8MM brass and that is 9X56 Mannlicher/Shoenaurer ammo and I have a supply of 8MM brass.
     
  15. locutus

    locutus Well-Known Member Supporter

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    Interesting experiences here.

    My military calibres, with the exception of .30-06 and 9MM, are all loaded to duplicate standard military ball, (practice/range ammo) or military match.

    I normally get 8-10 loads from MilSurp cases and 5-7 from commercial. I do not anneal.

    .30-06, I use Mil/Match cases for my hunting loads. These will usually last 5-7 loads. (These are loaded maximum. ~52-55 kpsi)

    For pistol, 90 percent of my loads are 9mm. I load all 9MM to +P+ and I use only MilSurp cases. 6-8 loads is common for my 9MM.
     
  16. alsaqr

    alsaqr Well-Known Member Supporter

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    Humpy:

    You have fired truckloads of M118 Match loads. Have you ever encountered any M118 rounds with the flash hole off center?

    i have some 1970 XM118 Match with some of the flash holes off center. It does not seem to hurt accuracy one bit.
     
  17. Dallas53

    Dallas53 Well-Known Member Supporter

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    This information is all fine and dandy, I guess if a person has access to specially made dies and reloading equipment, (which BTW, most of us don't.).

    I have been reloading going on over forty years, off and on, and I just follow standard reloading procedures for the ammo being loaded, and the type of firearms they will be used in. Seems to work out just fine, since I still retain all nine digits on my hands. (the lost one was not due to a reloading accident in any way, shape or form.)

    Brass cases are cheap. I get at least 15 to 20 loading's from a case, before I need to toss them. If a person is moaning about the cost of brass for special, or obsolete ammo, than I might suggest a less stressful and expensive hobby, like needle-point instead.
     
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  18. Hookeye

    Hookeye Well-Known Member

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    Everything I reloaded for was pushed to the max.
    Never worried about case life.
    Strictly loaded for performance (V and accuracy).
    Load em a dozen times, trash and buy new. No big deal.
    But then I wasn't high volume shooter and am now even less.
     
  19. Hookeye

    Hookeye Well-Known Member

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    I did run a couple hundred old WW .44 mag forever. Lost track of how many max loads.
    Got a couple cases to split eventually and threw em all away. They lasted as a group, way longer than I expected. Def got my $ worth.
     
  20. Hookeye

    Hookeye Well-Known Member

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    Should visit my dad, used to sell reloading stuff.
    Bet he's got a couple hundred new cases in .243, .44 mag, .30-06.
    I know the Norma stuff is stashed away LOL.
    Rumor is WW isn't as good as it used to be.