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fire formed brass

woodhogwoodhog Member Posts: 13,115 ✭✭
I've read and heard several times ,people speak of fire forming brass, and wonder what they are refering to. Anyone familiar with this term?


I've had a request from my opposite number over in the Reloading Forum to send these types of questions over to the guys who specialize in them.

Comments

  • mondmond Member Posts: 6,458
    edited November -1
    Once a factory ammo has been placed & fired in your rifle / pistol, the case has fired & formed to match your chamber. Hence fire formed [;)]
  • Tailgunner1954Tailgunner1954 Member Posts: 7,734 ✭✭
    edited November -1
    Using gunpowder to shape a cartridge case to the exact configuration as your chamber.
    The majority of reloaders don't bother with standardized chamberings
    You could consider only neck sizing to be a "type" of fireforming.

    Those who worry about it the most are those of us who are playing with wildcat and obsolete cartridges, where the shoulder shape/size/location is different than the "parent" cartridges. Example: look at a 300 Weatherby cartridge, than look at it's parent case the 300 H&H. Back when Wby brass was rare/non-existant everybody made their cases by fireforming (firing) a 300 H&H cartridge in their 300 Wby chambered rifle
  • joker19joker19 Member Posts: 110 ✭✭
    edited November -1
    FIRE FORMED cases were used specifically for the Ackley improvements to such rifles as the 30-40 Krag (becoming an Ackley improved) where the neck angle of degree changed a lot. Wildcat cases such as these had no commercial availability so you had to take a 30-40 Krag and shoot it in a Krag Improved rifle and form the neck thus FIRE FORMING the neck to the new rifle. Most cracked in the process but some did not. All wildcats did this for quite some time. Fire forming has nothing to do with a shell being fired in a specific gun and then only neck sized to repeat in the same rifle for accuracy.
  • Tailgunner1954Tailgunner1954 Member Posts: 7,734 ✭✭
    edited November -1
    Joker
    One slight "nit".
    You can (and some do) fireform for oversize/over long "stock" chambers, followed by necksizing, simply to increase the case life. The biggest group of people that do it this way are those reloading for belted cases. This allows them to use the shoulder to control headspace.

    The 30-40 Krag is kind of a bad example, as it's a rimmed case.

    Woodhog
    Below is a photo of the shoulder on a 243 Win (on the right) and a 243 Wade
    1-2-10003.jpg
    Below are a number of wildcats that have been formed from the 30-30 Winchester
    3-21-09003.jpg
    Finely, a 22-250 and a 22-250 AI which clearly show what fireforming can do.
    Std_vs_Ackley.jpg
  • zimmdenzimmden Member Posts: 237 ✭✭
    edited November -1
    Fireforming also adds much to the future accuracy of the case for reloaders. The poorest accuracy usually occurs on the first firing of new brass whether factory loaded or handloaded. Once the case is fireformed in a good chamber, the case will perfectly fit that chamber for many loadings. The headspace will be correct allowing very little expansion and the case neck will be very straight compared to new brass. This allows only neck sizing to be needed for much longer case life and better accuracy since full length sizing is now unnecessary until chambering becomes tight. These techniques work best in bolt action rifles.
  • jimbowbyjimbowby Member Posts: 3,496
    edited November -1
    [8D] Gotta agree with Zimm, my .223 Rem 700 gets remarkable accuracy with fireformed "MATCH" cases-


    quote:Originally posted by zimmden
    Fireforming also adds much to the future accuracy of the case for reloaders. The poorest accuracy usually occurs on the first firing of new brass whether factory loaded or handloaded. Once the case is fireformed in a good chamber, the case will perfectly fit that chamber for many loadings. The headspace will be correct allowing very little expansion and the case neck will be very straight compared to new brass. This allows only neck sizing to be needed for much longer case life and better accuracy since full length sizing is now unnecessary until chambering becomes tight. These techniques work best in bolt action rifles.


    [:o)][:o)] JIMBO
  • victorj19victorj19 Member Posts: 3,642 ✭✭✭
    edited November -1
    Fireforming is useful for pistol cases too. The 9x18 Makarov case has a slightly larger diameter and is 1mm shorter than the standard 9x19 round. I trim the 9x19 to 18mm, load them and fireform them to get the right diameter. Cases and gun are a bit dirtier but the following reloads are not. 9x19 cases are much cheaper and easier to find than the 9x18s.
  • 243winxb243winxb Member Posts: 264 ✭✭
    edited November -1
    On firing, the brass expands till the chamber stops it. 223Rem.jpg
    [url] https://saami.org [/url]
  • mondmond Member Posts: 6,458
    edited November -1
    quote:Originally posted by 243winxb
    On firing, the brass expands till the chamber stops it. 223Rem.jpg


    Good explaination , but not to be done !![:0][:D]
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