Combat Auto

Brass vs. Copper Jackets

7 posts in this topic

Ken, At SG-Amo I was inquiring about their 500 round bulk Remington 45 cal UMC FMJ....Sam's reply is below, note his reference to "some brass jacketed bullets in the loose".




From Sam:

It is basically the same stuff, UMC 45 230 grain FMJ brass case. The only difference is that I have seen some brass jacketed bullets in the loose, where as the boxed was typically copper jacketed. All that said I do not shoot it so I do not have that experience to comment on. We have sold a large quantity of both and no performance issues brought to our attention to date

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Most bullet jackets, and especially target-grade FMJ's are copper + zinc (and probably some other trace contaminants) which make them all "brass". The zinc helps with manufacturability


I know Montana Gold bullets (and others) are actually "yellow brass" colored though, maybe that causes some confusion?


To answer the OP's questions, if you're literally talking about pure copper vs. some high alloy brasses, it would be

(1) yes

(2) yes

(3) yes

But since I'd wager no manufacturer will tell you what specific alloy they use you'll have to try them out and see what works

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The only difference I have seen is that the closer the jacket alloy is to cartridge brass, the lower the velocity you get for the similarly shaped bullets in similarly loaded cartridges. Closer to pure copper is faster (probably higher pressure too). Thinner jackets mitigate this to some extent. THe only bullets I have loaded where this has been significant enough to matter have been Montana Gold. For the same charge and seating depth in the case, they run slower by a noticeable margin. As for pure copper, it fouls more because copper is softer, more ductile, and less springy. In rifle cartriges, you will find bullets with a thick pure (or darn near to it) copper jacket like the Scirocco II have a reputation for copper fouling the bore rapidly.


As for accuracy, I don't think it would matter more than quality construction and consistency. The only thing it affects that directly impacts accuracy is velocity, and with hand loads you can compensate for that.

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I sure brass bullets are outlawed ,if only jacketed are highly illegal because they will pass thru a vest easier than going thru butter.


You can be sure of a lot of wrong stuff. Doesn't make it true. There are plenty of dangerous game bullets that are solid brass there are solid gilding metal (i.e. brass) bullets form several major manufacturers at least for riffle bullets. That's on top of your sentence composition not making sense. JAcketed bullets go through vests easier? (no) Brass jacketed does? (no) I can't even tell what you are claiming.


The law as it stands is this :



"(B) The term `armor piercing ammunition' means-


(i) a projectile or projectile core which may be used in a handgun and

which is constructed entirely (excluding the presence of traces of other

substances) from one or a combination of tungsten alloys, steel, iron, brass,

bronze, beryllium copper, or depleted uranium; or


(ii) a full jacketed projectile larger than .22 caliber designed and

intended for use in a handgun and whose jacket has a weight of more than 25

percent of the total weight of the projectile.


© The term `armor piercing ammunition' does not include shotgun shot

required by Federal or State environmental or game regulations for hunting

purposes, a frangible projectile designed for target shooting, a projectile

which the Secretary finds is primarily intended to be used for sporting

purposes, or any other projectile or projectile core which the Secretary

finds is intended to be used for industrial purposes, including a charge

used in an oil and gas well perforating device."


[secretary means Secretary of the Treasury, in reality determinations

are delegated to the Technology Branch of the Bureau of Alcohol, Tobacco

and Firearms (ATF)]

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