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Thread: Primer Cup Thickness

  1. #16
    Join Date
    Apr 2008
    Posts
    27
    Yesterday while reloading I saw that installed CCI 400 primers were a couple of thousands above the brass base, so did some measurements.

    Brass: Once fired Black Hills Match 223 Rem
    Primer: CCI 400

    New Primer Height (using dig mic): 0.125
    Primer Height after deprime (not fired): 0.121
    Primer hole depth in brass: ~0.116

    I had to increase primer hole depth to 0.125 to reliably achieve the primer strike surface below the brass base surface.

    As I am relatively new to reloading HP rifle is this a normal situation?

  2. #17
    Join Date
    May 2003
    Location
    Phoenix, Arizona
    Posts
    633
    Rangerat, while we expect primer pockets in brass to be at a compatible depth with all commercial primers, it's always worthwhile to check them when you get a new lot of brass. Given the usual measurement errors that crop up, I'd say your brass is within specifications, although it's at the shallow end and your primers are at the tall end of that spec. Uniforming is an absolute must in that situation.

    SAAMI standards for small rifle primers and primer pockets are as follows:

    Sm. Rifle Primer Pocket - Depth: .117" to .123" - Diameter: .1730" to .1745"
    Sm. Rifle Primer - Height: .115" to .125" - Diameter: .1745" to .1765"

    while we're at it...

    Large Rifle Primer Pocket - Depth .125" to .132" - Diameter: .2085" to .2100"
    Large Rifle Primer - Height: .123" to .133" - Diameter: .2105" to .2130"

    German Salazar

  3. #18
    Join Date
    Sep 2007
    Posts
    1,410
    Joe, without any doubt, heating will change the hardness of the cup. It is
    work hardened in forming and annealed by heating. It will require that much
    heat, Yup. Scraping and removing the contents of the cup can change
    the measurements of the cup. I would also doubt that brass in sheets
    can be held to .001 and still be feasible financially. At any rate
    tollerances must come into play. Remington once had an issue with
    there cup material and that cost them dearly, leaving 7 1/2 users
    with pitted bolt faces. That is a serious consideration for any one
    making primers and adds to the cost. In a much older book,
    Col. Narramore , offers great insight into primers. Explaining both
    sensitivity and durability along with manufactureing, much of which
    has been mandated by the Military. We must remember that we
    represent a small market as BR shooters.

  4. #19
    Join Date
    Jan 2004
    Location
    Northern Dakota Territory, 1-days ride SW of Ft. Ransom in LaMoure Co.
    Posts
    330
    Bob -- Good of you to bring that up about problems that were endured!!!
    I have an XP100 bolt that is pitted from back in those times...forgot about that and the cause



    German -- Thanks You!!! for providing the SAMMI specs.... I never had those before.
    Your flash pictures to primers from a couple years back were very good info as well... A late Thanks for them as well !!!!
    I always enjoy your writes/posts !!!

    Happy Shooting
    Donovan Moran

  5. #20
    Join Date
    May 2003
    Location
    Phoenix, Arizona
    Posts
    633
    Thanks, Donovan! I think you'll like my primer article which should be in the June PS, I'm working on "Part 2" of it now. Meanwhile, to keep you entertained, here's a good article, not terribly technical but lots of interesting items, written by a good friend. I have it on my website, but I might be pulling the website down soon, so save it if you like it.
    http://www.shootersjournal.com/Featu...39;tGoBang.pdf

    German Salazar

  6. #21
    Join Date
    Feb 2003
    Posts
    2,606

    Bring me into the light please Sirs

    Why is ther such interest in the dimensional aspects of primers?

  7. #22
    Join Date
    May 2003
    Location
    Phoenix, Arizona
    Posts
    633
    Wilbur, speaking only for myself, I'm endlessly fascinated by primers - small item, small mind....

    Seriously, as a long-range shooter, primers are very important to load performance at 600 to 1000 yards, so I put a lot of energy into examining and testing them. In the world of competitive Benchrest, they seem to be less of a factor, so I can understand the relatively lower interest level.

    German Salazar

  8. #23
    Join Date
    Feb 2003
    Posts
    151
    Wilbur
    Last winter I built 3 new rifles. Two for BR and one for hunting.
    Actually, the hunting gun I have had for over 25 years and I rebarrelled it.
    With the same old loads I have been using all along, I pierced a few dozen primers. (Yes, a few dozen)
    This lead me on a crusade to find out why I was piercing primers.
    After a couple of months of trials and tribulations, I decided to share my findings with my BR friends as I found it to be particularly interesting and informative.
    Joe Cowan

  9. #24
    Join Date
    Feb 2003
    Posts
    151

    Another thought about Primer thickness and hardness

    I have had problems in the past while fireforming brass, getting the round to go off.
    Especially when the shoulder is being blown out a good bit.
    When relying on bullet seating depth for headspace, it is sometimes hard (at least for me) to get a good enough strike on a primer with a thick cup.
    The info listed above will be considerable help in choosing a primer with a thin cup to get a sure fire the first time.

  10. #25
    Join Date
    Dec 2003
    Location
    washington.........STATE that is.
    Posts
    8,205
    Joe,


    That specifically was one of the things I was testing. My findings were clear and unequivocal. You WILL NOT get the jammed bullet to hold the case back even with a thin cup.

    And just getting the case to fire does NOT make for good brass.

    Proper fireforming requires solid shoulder support.


    sorry if it seems like I'm changing the subject this fireforming thing is one of my Hot Buttons.....


    LOL


    al

  11. #26
    Join Date
    Feb 2003
    Location
    Billings, Montana
    Posts
    1,465
    About ten years ago I was having trouble fireforming some AI cases using CCI 400 primers, with lots of failures to fire Although Winchester primers are supposed to be less sensitive than others, they gave 100% ignition with nothing else changed. Although the CCI 400's appear to have thinner cups they must be harder because they tend to not flatten and/or crater like WSR's or F205's.

  12. #27
    Join Date
    Dec 2003
    Location
    washington.........STATE that is.
    Posts
    8,205
    About 15yrs ago I was big into shotgunning. I'd spent 10hrs on the patterning board and had worked up a great load using AA hulls and 700X powder (If I remember right). All was great, I used this load with success for some time, it came right out of the reloading manual and it patterned great, good vel etc.


    One night I had to load up 500rds for our Thanksgiving Day shoot and I ran out of the Win primers.

    No problemo, I had cases of others.......so I just grabbed a brick of federals and went to work.


    Next day was cold, as we progressed into our shoot about an hour one of the guys started to get some odd sounding shots from his 870, he missed-whined-stuttered some birds-whined-got unmercifully scorned for his complaints------and all of a sudden had a hangfire that popped AFTER the action was open.


    SPOOOOKY!!!


    We stopped the action for an hour while we sorted it out. The buckets of rounds were cooling down from room temp......his was right by the corner of the building in the wind. Using his loaded rounds we all got hangfires and poopers.


    The SAME LOADS but with Win primers were going on like gangbusters.

    I set all of the Fed-primed loads back into the heated building and by carrying them in a pocket and using them warm we got thru the day. Later I burned them up for crow loads in the summer.


    I called Federal all in a huff.

    The technician that I talked to was a gentle and understanding soul......... he gave me a dissertation on reloading components and the use thereof. He explained how different powders had different ignition characteristics and different primers had different burn rates and brisance..... Even different chemical compositions, different actual priming compound mixtures. ALSO that priming mixes changes and evolved over the years, that it was a real pain when a problem was "cured" with a mixture but they couldn't publish because there were still old lots out there..........He furthermore stated that the loading manuals tested combinations through a wide range of conditions and also that they had characteristics charts that allowed them to spot problems and tailor primers to powders.......etc etc etc and ad nauseum, I was starting to feel flimflammed.



    Me being a sneaky and belligerent unbeliever who was used to having snarky salespeople blow warm air up my skirts I asked him to read me from his list of "bad combinations".....


    Combination #3 with a star by it was "Fed 209's lot numbers between XXX and XXX NOT compatible with 700X, ignition problems under 60 degrees, NOT recommended for any use"........


    !!!!!!!!


    KNOCked the pugnaciousness right outta' me.......


    The guy then actually sent me 2000 primers for FREE!!! It's always left me with a soft spot for Federal products. I owe 'em.



    My point is this:

    I essentially ignore "burn rate charts" except to group powders near each other.

    I ignore claims of "hotter" or "cooler" primers because I've had primers act "hotter" with one powder and then "cooler" with another. What I'm saying is, using 2 brands of primer and 2 brands of powder the trends may well REVERSE.

    I start with stuff that's got a track record and NEVER change even so much as the primer without backing off a good bit and NEVER assume that a primer/powder combo will work until it's been run through the wringer of time and temp.


    I guess when it comes to primer/powder combo's I just never assume.


    I still remember the way my brother-in-laws safety glasses looked when he turned his soot-blackened face toward me and asked "NOW can I whine?"






    al

  13. #28
    Join Date
    Sep 2007
    Posts
    1,410
    Quote Originally Posted by Joe View Post
    I have had problems in the past while fireforming brass, getting the round to go off.
    Especially when the shoulder is being blown out a good bit.
    When relying on bullet seating depth for headspace, it is sometimes hard (at least for me) to get a good enough strike on a primer with a thick cup.
    The info listed above will be considerable help in choosing a primer with a thin cup to get a sure fire the first time.
    Joe, I must be confused here, in a standard 6 BR , long throated
    for 107's why are you blowing shoulders out a good bit ?? or is this not a standard chamber??

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