Could someone explain the basics of designing and forming custom cartidges?

Discussion in 'The Ammo & Reloading Forum' started by phobos, Nov 12, 2011.

  1. phobos

    phobos New Member

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    Alright I would love do design my own firearm caliber(s) as well as form them. theirs only one slight problem I cannot afford a book on it and would like to get to griped with the basics of designing and forming my own unique custom calibers. this also ties in with my dream of venturing into the trade of the gunsmith as well or a profession. Thous I would doubt my sucessfulness in the marketplace.
  2. jack404

    jack404 Former Guest

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    Phobos, your in for a long road , and you'll need the book for lot's of resons , most importantly is so you dont

    re-invent the wheel..

    but design is fun, and sometimes dangerous

    know your platform

    chamber pressures are easy to screw up and explode even a Lee Enfield.. ( done it twice now , but did so knowing it was gonna be close .. and used a string ..)

    theres a lot of work needing to be done on shoulders for current cases ,

    with the technology now available to examine how poweder burns and the physic's of it better known too , ( High Speed hydro fluid dynamics ) we now see that shoulders of cases have been a big issue with case pressure

    i'd suggest going there first , the calibers have been pretty much cut to deal unless you wanna look at rim fire . there is a need to cut the .22wmr to .17 along the same lines

    good luck eh

    your design is always based on a requirement

    any plans, design for anything, must be for a requirement otherwise you get off track too easy , make a goal and go for it ..

    so look at your requirement to target a gap in the market or a need or your personal game or target choice ..

    .22lr not enough but .22 wmr too much ?

    looking for a 1000 meter rifle ?

    2000 meters

    these are basic requirements , things to design for

    a better pig stopper or fox killer, while leaving the pelt undamaged, these too are requirments, and how you focus your design

    so for a fox you'd look at smaller projectile size rather than say a .338 or .416

    these are good killers but arc at lower velocities so end up high end velocity rounds

    so your looking small ( less damage to pelt) but flatter trajectory for accuracy ( speed 0

    so a round like the 22.wmr but not quite the .17 hmr ( too high speed and explosive to pelts if not head shot) would be good and away you go

    thats the basic's

    then theres the technology

    straight case shouldered case powder load , burn , expansion rates as affected by case

    chamber pressure for the rifle type your looking at

    all these things are then accounted for

    then you start shaping ..

    once you have a few test loads

    then you need to test them

    do you have your custom rifle yet ? no ? good ...

    build a bench block like a big receiver and bolt , into this you can run a pressure tester and be safe and not destroy a rifle

    this will give you a good reading on pressure

    it'll also allow you to get basic MV tests and such done

    if all these work out ok , then start on a rifle

    but often you'll end up going back and starting over at the bench block stage

    thats ok , after a few goes you'll know yourself what'll work and what won't

    its all learning

    cheers
    Last edited: Nov 12, 2011
  3. dustydog

    dustydog New Member

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    Get a chamber drilled,reamed and ground with both ends open in a piece of barrel grade stock about 2 1/2 " in diameter and roughly 1/4"longer than the proposed case.Build a clamping rig that has a swing down breech face and firing mechanism ,attach to the chamber blank at rear.Attach to heavy bench.Take a under diameter basic brass blank case that is roughly .030 undersize for the chamber(except the head area,that must have full support),prime and load with 10-15 grains of Bullseye.Stuff cotton in the case mouth,chamber the primed case,close breech,fire.Extract,trim to proper length.
  4. reynolds357

    reynolds357 Former Guest

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    The first thing you are going to have to have is a pressure testing barrel.
    Why would you want to develop cartridges? Almost anything you can conceive already exists. Me and some of my buddies have tweaked a few wildcats, but I am definitely not up to starting from scratch on one. Pretty much any cartridge you can think of has been necked up and down to everything, angles changed on body, necks blown out, rounded over, etc. etc. My advice would be to dream up what you want and then do some extensive research to see if it already exists, it has probably already been done. I had the bright idea I wanted to neck a full length .300 wby down to .257. I told my friend what my idea was and asked him to call and have a reamer made for it. He said, "I dont have to because I already have a reamer to do it." He said "Roy Weatherby came up with it but never production chambered it due to 500-600 round barrel life."
  5. BillM

    BillM Active Member

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    Pick up a copy of "The home guide to cartridge conversions" by George
    Nonte. The basics of how to form darned near anything out of something.


    Then get a copy of "Designing and Forming Custom Cartridges For Rifles and Handguns" by Ken Howell

    Just curious---what market is it that you think exists for a cartridge
    design that hasn't been tried?

    Hmmm--just read your first post again "one slight problem I cannot afford a book on it"?????

    If you can't afford a book----you sure as heck can't afford to get into
    custom castridge forming!!:)
  6. reynolds357

    reynolds357 Former Guest

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    Custom cartridge building is a money pit. My friend has designed a .30 that is faster, more efficient, more accurate, and has better barrel life than the .30-378. He has sold less than 20 of them because you have to create a market for them. You then have to try to get someone to produce brass for it because the vast majority of people are not going to buy a rifle they have to form brass for and that will be headstamped for the parent cartridge. He also has a 6mm that beats the brakes off the catbird, but SAME PROBLEM with selling it.
  7. jack404

    jack404 Former Guest

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    spot on ...

    again if you missed my hint ,

    i'd love to see a .15-.17 straight wall rimfire like the .22 magnum , i think it'd be brilliant small to light game round ..
  8. phobos

    phobos New Member

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    I have some reference of three pre existing rifle cartridges though. I can't afford the books right now but maybe in the near future. plus I would need to order them via the phone. problem with the books you mentioned is that they are rare and hard to find in the UK. they cost £200($400) for the first book and £108($208) for the second respectively. then again that kind of rarity is what I expect from the protectionist government over here in the UK.
  9. jack404

    jack404 Former Guest

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    phobos , we have the same hassles in Oz , Amazon.com mate .. second hand can be cheap , 3-4 books for $150 USD inc shipping to OZ , the UK would be cheaper
  10. BillM

    BillM Active Member

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    Holy $#%^%@!!!!!!!!!

    I just looked at Amazon for the Nonte book. USED prices starting at $100+,
    a new one for almost $700! Used one in the UK for $1600+.

    Just went and dug mine out of the pile in the reloading room and put it in the safe.:eek:
  11. jack404

    jack404 Former Guest

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    do so mill my 1950's book collection i paid $30 for ( plus trailer hire to get it home ) is worth more than i'll ever be..
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