Cornmeal forming bad on a new barrel??

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by jb1000br, Jan 22, 2004.

  1. jb1000br

    jb1000br Well-Known Member

    Messages:
    1,307
    Joined:
    Jul 8, 2003
    In many wildcats it is advisable to use a little bullseye and a case full of cornmeal topped of with a wad of some kind to form cases to save barrel wear from firing bullets.

    I have heard this may be bad for a barrel but dont see how cornmeal could harm barrel steel.

    can cornmeal fireforming be bad for a barrel?

    looking for some facts and actual experience here to set this straight.

    TIA

    JB
     
  2. sniper2

    sniper2 Well-Known Member

    Messages:
    948
    Joined:
    Jan 10, 2003
    Why would you need something in the case???
     

  3. jb1000br

    jb1000br Well-Known Member

    Messages:
    1,307
    Joined:
    Jul 8, 2003
    if its the "wad" you are referring to--it is just a patch shoved in the top to keep the cornmeal from spilling out.

    JB
     
  4. BountyHunter

    BountyHunter Writers Guild

    Messages:
    4,803
    Joined:
    Jun 13, 2007
    I have found that simply necking up to next size larger and then necking back down and leaving small shoulder on neck where bolt will barely close works just as well and hell of lot easier.

    BH
     
  5. BountyHunter

    BountyHunter Writers Guild

    Messages:
    4,803
    Joined:
    Jun 13, 2007
    [ 01-22-2004: Message edited by: BountyHunter ]
     
  6. Bluebeemer

    Bluebeemer Well-Known Member

    Messages:
    62
    Joined:
    Mar 21, 2003
    I have never had a wildcat cartridge, but have witnessed others doing something as you say. Speedbump was forming 7MM RUM cases before they were available from Remington in a similar manner. But, I think he had to start using oatmeal because their wasn't enough cornbread for supper! Good luck ... Mike
     
  7. Mysticplayer

    Mysticplayer Writers Guild

    Messages:
    1,459
    Joined:
    Jul 27, 2001
    jb, I use that for several wildcats I have owned. Never had a problem with cornmeal and barrels. In fact, I will suggest that it may "lap" the barrel a bit.

    Just use a piece of paper towel over the cornmeal to keep everything in place. All will blow out and nice cases formed. Works very well.

    If cornmeal could damage a barrel, could you imagine what an oversized copper slug being driven down it at up to 65000psi would do?

    Jerry
     
  8. 6.5 Bandit

    6.5 Bandit Well-Known Member

    Messages:
    123
    Joined:
    Mar 2, 2003
    I have heard others doin this as well but never did it myself. I dont see how it would be hard on the bbl though.. I usually fireform with regular loads..

    6.5 Bandit
     
  9. Mikecr

    Mikecr Well-Known Member

    Messages:
    4,269
    Joined:
    Aug 10, 2003
    I'm planning on COW FF for a wildcat. Even though the pressure will be there, heat and the cutting torch effect on the throat will surely be less.
    And my max accurate barrel life may be extended to a whopping 700 rounds!
     
  10. speedbump

    speedbump Well-Known Member

    Messages:
    397
    Joined:
    Mar 28, 2002
    jb,

    As blubeemer stated, I've done alot of this in 7mmRUM ( very funny Mike [​IMG] ). It stinks like cat $#!^, is a general pain to do, & you get funny looks at the range. BUT, I'd much rather do that than blast full house loads through an overbored rifle just to get brass fireformed.

    Grits, toilet paper, Unique, & cheapo primers are FAR lees expensive than full-house match ammo.
     
  11. jb1000br

    jb1000br Well-Known Member

    Messages:
    1,307
    Joined:
    Jul 8, 2003
    Jerry--that was my thought too but i had heard it could be bad for the barrel.

    JB
     
  12. 4mesh063

    4mesh063 Well-Known Member

    Messages:
    374
    Joined:
    Dec 8, 2002
    Jason,

    I don't worry about barrel wear, but, If I did...

    I'd buy a mold for 30 or 6.5 bullets, whatever fits in the gun, and shoot lead bullets to fireform. It's a rather well known idea that lead bullets don't wear a barrel. Why not fireform with cast bullets at a much lower charge?
     
  13. LDO

    LDO Well-Known Member

    Messages:
    251
    Joined:
    Sep 23, 2003
    i have fireformed many wildcats with bullets and powder and accuracy can be outstanding,tried the COW method once,i just didnt feel it was worth it when u can get some great accuracy with bullets and powder while at the same time breaking in the barrel,and practice with the new rifle.my-2-dave
     
  14. Brent

    Brent Well-Known Member

    Messages:
    2,537
    Joined:
    Jun 12, 2001
    I neck down the 338 Lapua to 30, then form with COW and a toilet paper on top.

    26-30gr of 800X, and COW jammed in tight with a rod = fully formed every time. [​IMG]

    If I wasn't forcing the shoulder "back" to be able to chamber it, which makes the longer neck, I might do what Bountyhunter does too, but then again I have to turn necks to .125" to chamber a round, so again, I can't.

    COW does not stink, never tried cornmeal. Instant COW seems less abrasive, if it were a problem.

    If I was blowin the shoulder forward and din't have to fit the necks, I'd seat the bullets into the lands and go clang some steel. The case surely doesn't know it's not formed yet, and it will be before it ever hits peak pressure, I assure you.

    28gr of 800X and COW in the 30-338 Lapua Imp runs about 37,000 psi.

    With this method during testing, 15gr on up formed the cases perfectly, the only difference was the very base of the neck where it's real stiff ends up getting more brass reamed out from the K&M fluted cutter than really needs to be, so I kept uping the charge until it blew out there a couple more thou.

    Optimally, nothing down the bore except your tuned loads would be nice. [​IMG] Some guys have a forming barrel chamber and use it. Necessary? Better, but I'm not sure it's really woth it IMHO.