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Bi-metal or steel jacket for 'break in'

gotstolefrom
I was asked a question that I answered with my opinoin, and now I'm seeking your's.

Several manufacturers specify a barrel break-in procedure.
In your opinon(s), should steel or bi-metal jackets be considered differently from copper for any reason, as long as all other requirements were followed correctly.

Thank You in advance for a full listing of replies.
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Comments

8 comments

Date Votes
  • vdms55
    gotstolefrom
    it would be my opinion that one use same bullet he intends to use throughout the life of the firearm for the breakin process. i have done this several times with hunting rifles and have always had the results i was seeking.
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  • cussedemgun
    gotstolefrom,

    "Copper bullets" are actually "gilding metal"

    A quote from "Firearms Encyclopedia" by George C. Nonte, Jr.

    Guilding metal - A cupronickel alloy used almost universally for bullet jackets, though replaced to some degree by mild steel in a few European countries. Formulas vary considerably, depending upon the manufacturer, the bullet and its use. The proportions may vary from 60% copper and 40% nickel to 87% copper and 13% nickel, plus minute amounts of other materials.

    Guilding metal is ideal for bullet jackets because of its unique property of being self-lubricating, allowing it to be used in steel barrels at high velocities without being rubbed off and deposited in the bore to accumulate as metal fowling. Reference is sometimes made to this property in trade names such as Winchester's "Lubaloy" and Dynamit Nobel's "Nobeloy"

    In addition, gilding metal is easily and economically worked, reasonably low cost, and yet possesses sufficient strength for virtually any sporting ammunition requirement.

    During wartime and other periods of copper shortage, mild steel thinly coated with copper or an alloy with similar properties is often substituted for gilding metal in bullet jackets. Bullets so jacketed cannot be visually identified, but a magnet will attract them.

    End of quote.

    My thoughts; For a sporting arm, stick to sporting ammo. If you are shooting a rifle with a chrome lined bore, it was built that way to stand the extra wear factor of steel bullets.

    Jim

    EDIT: XXCross, in metallurgy "I think" don't cut it! An alloy can display totally different characteristics from the parent metals. That is why the science of metallurgy is a specialty study aside from engineering or chemistry but taking both concepts into consideration.

    For gilding metal (bullet jackets) a high heat alloy with good wear properties is needed.

    Jim
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  • XXCross
    "The proportions may vary from 60% copper and 40% nickel to 87% copper and 13% nickel"
    I DON'T THINK SO!
    Bullet jackets don't contain any niclel. Nickel is a hard, britle metal that would raise hell with anyones gun barrel. I think you must have meant "zinc".
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  • jethro
    This is just my opinion, but if the thickness of the copper over the steel jacket is thick enough to stay on the steel as it travels down the barrel, it should be fine.

    Thin cross sections of mild steel are very soft. With a sufficient thickness of copper over it, the barrel should be protected.

    Look at a recovered round and see if any steel is showing. If so, then I don't know that I would keep shooting.

    Mike
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  • tsr1965
    When you are breaking in a barrel, what you are doing is burnishing all the mirco burrs, and some of the button chatter out of the barrel. I would use nothing harsher in my barrel than nescessary. That being said, a copper jacket only, no bi-metal or steel.

    Best
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  • zimmden
    Breaking in a barrel is more a matter of cleaning the bore properly (often)while shooting a small number of shots between cleanings. The object is to smooth the rifling while removing carbon and copper fouling before it builds up. After 10 to 20 cleanings you should feel less drag on the cleaning rod as the bore becomes polished. Benchrest shooters who spend $500 to $1000 per barrel recommend this. Bullets should not have hard jackets that might damage rifling. Bob
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  • jonk
    One can also hand or fire lap the bore to speed the process.

    I personally don't see as it would matter, as you are just wearing out the imperfetions. However just due to availability, I'd use standard (if fairly cheap) bullets.
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  • JamesQuinn
    quote:Originally posted by XXCross
    "The proportions may vary from 60% copper and 40% nickel to 87% copper and 13% nickel"
    I DON'T THINK SO!
    Bullet jackets don't contain any niclel. Nickel is a hard, britle metal that would raise hell with anyones gun barrel. I think you must have meant "zinc".


    Not so. Cupro-nickel alloys have good properties of strength and formability. The fact that they contain nickel does not mean that they have the properties of nickel. As one example, nearly all European cars use cupro-nickel brake lines. They are more easily formed than steel, more resistant to fracturing. Excellent alloys for bullet jackets. Of course jackets can also be zinc-copper, and even plain copper. The old "lubralloy" copper coated bullets had just a very thin (less than .001") copper wash which was nothing but decorative and served no purpose other than a sales gimmick.

    True jackets are formed in a stamping press, then filled with lead bullets.
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