Results 1 to 6 of 6
  1. #1
    Join Date
    Dec 1969
    Posts
    246

    Default reloading (or cut down) star crimped .308 blanks?

    can you reload star crimped .308 blanks? if not, can these be cut down to fit 7.62x39 or something else? I see cia's monthly special for boxer primed blanks and started wondering.......

  2. #2
    Join Date
    Dec 1969
    Location
    Brisbane, Australia
    Posts
    5,093

    Default NO NO and NO

    Blanks made specifically as "long profile" are made from different brass to ball cases (softer), and a lot of the European ones have a smaller than normal flash hole (if Boxer) or they may be Berdan...

    As to making 7,62x39, Forget it...the 7,62 Nato case head is .470", the 7,62x39 is .445" ,
    a rather big jump...It can be re-swaged down with four or five sets of "Ring dies", Trimming, recutting extractor groove and rim, and re-reaming the distorted primer pocket...cheaper to buy new 7,62 x39 cases.

    The Only thing we recycle 7,62Nato Long blanks is into 7,62 Nato short( B/A Rifle) Blanks ( by cutting off the profile, and then star crimping the remaining shell,) or we can reform it to 7,9x33 Kurz ( Sturmgewehr) BLANKS only. They are the same body dimensions, just shorter ( with a Bullet profile) and they work wonderfully...Oh ,and we have the correct decapping Pins for HP type small flash holes.

    Otherwise, use as Blanks, and then scrap the brass ( or use the cases to make Powder measures etc).

    Doc AV
    AV Ballistics. Film Ordnance Services

  3. #3
    Join Date
    Dec 1969
    Posts
    246

    Default

    thanks. I wasn't clear in my initial request but you correctly read my mind--don't alter the blanks to fire a projectile in any caliber.

  4. #4
    Join Date
    Oct 2007
    Location
    Melbourne, Australia
    Posts
    993

    Default Curious............

    Hi Doc,
    I am curious about the statement blanks use a "different brass". It seems illogical.

    Apart from the fact that Bertram says he uses the same brass to make his blanks (as far as I have heard), it surprises me a factory would have brass in stock which was unsuitable to make live ammunition. How do they tell the different materials apart?

    Why would they risk it getting mixed up (unless blanks were made at separate factories) "in process" and end up with dangerous live ammunition? Is there a metallurgical reason to use difference alloys for blank cartridges? Are just the steps in forming the cases different (eg annealling?) so that the brass is the same but the treatment of the brass is different? Is the brass for blank cartridges cheaper (due to alloy content) or thinner, and the driver a cost saving? I could understand that a factory using the same cupping draws for all cases (since the tooling would be the same for the cupping draws), but the final steps to "long draw" the blank cases ends up with a case which is thinner (but which started off from the same thickness of sheet)

    A lot of questions, but I am just curious..........

  5. #5
    Join Date
    Dec 1969
    Location
    Brisbane, Australia
    Posts
    5,093

    Default Brass for Blanks

    In the old days, before "full profile Blanks" the rule was Blanks were made from once-fired Brass,from "remanufactured"(pulled down) Ball, from cases rejected "In manufacture" and other various sources (such as Lot over-runs or unlotted (unchecked) Ball brass.) FA and Lake City did this up to the 1960s, when they started using New cases; they had run out of Recycled WW II ammo brass, old stock overruns, and once fired brass.

    With the improvement of Blank manufacture, most Blanks nowadays are made from Virgin brass sheet, but it may be (1) not quite up to Ball metal specs ( slight impurities, etc),(2) it may be "old sheet";(3) it may be uneconomical to re-roll to correct Disc/Cup thickness for a particular calibre. Economy of use of brass, which is costly, makes secondary use essential.

    Blanks are drawn from slighly thicker cups, and bigger discs, to ensure the correct OAL of the profile. This also results in a Thicker wall on both the Body and the "Profile"
    If you cut through a Nato Blank, you will find that the false Bullet profile only reaches normal neck thickness at the very end of the profile, where it is crimped. At the real neck, it is quite thick walled, to prevent the splitting of the crimp propagating Backwards into the body ( which still occurs occasionaly, especially in an MG that is running Hot).

    This thickness of the neck etc, is one reason for Not using cut down blanks for Ball cases ( the neck is too thick for the normal bullet ( and also the finished external neck diameter...causing chamber "crowding" and increased pressure.

    Furthermore, to get the correct Long draw, the anneals during Cup drawing are more intense, to allow for good flow of brass to make the profile eventually. That results in a slightly softer head wrt to the rest of the body ( and softer than true ball cases). Again, softer heads are a NO-No for higher pressure Ball rounds.

    Ball runs at 48-52000PSI, Blanks just run at a maximum of 25,000 PSI, with a 15,000 max. "Port pressure" to operate gas systems ( a Garand uses 10,000 PSI Port pressure)
    With improper venting of a BFA, it is possible to crack a Garand receiver into uselessness.

    Another factor is that Hirtenberg are well known for using a small flash hole in both 5,56 and 7,62 cases, to prevent them being recycled by (illegal) European civilians into ball ammo cases. The primers (boxer) are the same as normal, but if you try to decap with a RCBS or Lee decapping Pin, you're in trouble ( bent pin, or stuck pin, jaming the press as well.
    For the thousands of HP brass Blanks we cut up and recycle into other Blanks ( .380, 9mmP, 7,62Tok, 7,9 Kurz) we use a special small diameter decapping pin to avoid grief...we do have to segregate HP cases, but they have a bright red primer lacquer, and stand out in a mess of Aussie, Belgian and US Blanks. The cases are lathe-trimmed first into cylindricals, before decapping and re-sizing.
    Other makers of Blank ( such as the Germans, Portuguese (back when) and FN all use Berdan primers, so reloading is a specialist job, anyway ( we do it all the time, the cases are top quality anyway, for Blanks.)

    Mixing up of Blank and Ball drawing...most Ammo factories these days have such complicated "in line" machinery ( SCAMP or Manurhin) that to change from one type of load to another takes up to 2 months re-setting all the tool heads, punch travel etc. ADI makes 5,56 blank once every three years, and then it runs blank for almost a whole year, before going back to Ball, on the same machine line. No chance of "mixing it up" there.

    Older factories which have the old style Single job machines for each stage, could have problems, but the multiplicity of machinery makes "separate production Lines" ( even separate Buildings) viable in keeping Ball apart from Blank manufacture ( especially since Powders are vastly different, etc. And production can be run concurrently.

    Bertram is not an indication of large scale military production, because whilst he does use single Job machines ( old US and Aussie Military factory machines), he is "small fry" in the production stakes...and uses single sized cups for a lot of calibres ( ie, one size fits all, so to speak.)

    Steel cases are a different matter. They just adjust the diameter of the cup-disc to allow for the extra profile length, and the rest is as for Ball cases ( I have dismantled and cut back various Combloc Steel blanks, and the finished cut-down Blank case matches a normal Ball case in thickness and weight.

    So , modern Blanks have one use Only...either scrap or other ( semi ) professionally made Blanks of a derived calibre.

    best regards,
    Doc AV
    AV Ballistics.

  6. #6

    Default

    I remember seeing US military 5.56 blank cases with "dotted-line" bands on the cases, either just below the shoulder or midway down the case, it also seemed that the cases were much darker than normal ammo ... this was circa 1971 or so ... cz

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •