[hguant]

Sorry, but this is entirely incorrect.

First, terms - brass is not used to "jacket" a bullet. Brass is used as the case material for the cartridge. Steel, and nickel plated steel are some times also used here. "Jacketing" (as in, Full Metal Jacket) refers to the material that wraps around the exterior of the projectile. As far as I'm aware, the material used here is almost always copper, or a copper alloy (cupronickel).

The US standard bullet is the M855. It's a lead core with a soft soft steel penetrator at the tip, that's jacketed with copper.

There's an advanced version of the M855, the M855A1, which is an entirely steel slug, jacketed with copper. This bullet has better terminal performance at longer ranges, and slightly better armour piercing capabilities.

The US army standard training round is the M193. It is a lead bullet jacketed with copper. Interestingly, it in many ways has better terminal performance than the M855 because this is the bullet the M16 and M4 rifles were designed around, and the M855 only exists because of NATO politics.

There are no bullets in the US inventory, to my knowledge, that use a copper core. Copper is simply far too expensive to be used at that scale, and, as you pointed out, reduces the weight of the projectile which has negative effects on terminal performance.

"Why are bullets jacketed in copper" you might be wondering here - when rifle cartridges were invented, they still used black powder, and all bullets were lead. When smokeless powder was invented, it became possible to have more explosive power per unit of volume. However, this had two negative effects - one, the lead projectile would either disintegrate, or became entirely inaccurate, at the speeds it was accelerated to. Second, the force of the bullet against the rifling of the barrel was rubbing away metal from the bullet, leaving lead deposits which fouled the gun and made it inaccurate. All steel bullets solved this problem, but increase the wear on the barrel. The solution was to coat (jacket) each bullet in a thin layer of copper, which was stiff enough to withstand the force of friction in air, while also softer than the steel barrel and reduced wear and tear on the rifles

[georgewh]

M855A1 is copper core. Lead free was a requirement as lead contamination from ranges was becoming a problem. See: https://www.army.mil/article-amp/106710/picatinny_ammo_goes_...

[hollerith]

I'll concede that my assertion that the jacket is brass might be incorrect. But you're about 13 years out of date when you write that

>There are no bullets in the US inventory, to my knowledge, that use a copper core. Copper is simply far too expensive to be used at that scale . . .

Photos of cross sections of the M855 and M855A1:

https://twitter.com/izlomdefense/status/1202516482082639872/...

M855 has a lead plug behind a steel penetrator. M855A1 has a copper plug behind a steel penetrator. So, I stand by my "copper where the lead used to be". I never said there wasn't a steel penetrator.

From https://en.wikipedia.org/wiki/5.56%C3%9745mm_NATO:

>For general issue, the U.S. Army adopted the M855A1 round in 2010 to replace the M855. The primary reason was pressure to use non-lead bullets. The lead slug is replaced by a copper alloy slug . . . The U.S. Marines adopted the Mk318 in early 2010 due to delays with the M855A1. This was a temporary measure until the M855A1 was available for them, which occurred in mid-2010"

As you probably know, most combat soldiers in the US Army and Marines carry a rifle (usually an M4 these days IIUC) that fires 5.56×45mm NATO, so it is probably the ammo type that the US military uses the most of.

[hguant]

This post is a master class in why you shouldn't get all your information from Wikipedia. Press releases are not reality.

Yes the M855A1 was developed and started operational testing in 2010. However, it wasn't available to anyone who wasn't forward deployed until...my memory says 2015. The M855 is still used on post because a) it's cheap, and ballistically similar to the M855A1 and b) the production lines at Lake City are still geared for them

The Marine corps didn't formally adopt the M855A1 until 2017/2018. Brass didn't like it because it broke the feed ramps on machine guns. There was a big procurement SNAFU about this.

Marine corps times article on the matter:

https://www.marinecorpstimes.com/news/your-marine-corps/2017...

I get that you're trying to be snide because you were so publicly wrong, but your tone here really just makes you sound like you're trying to sound smart about something you know nothing about. Something to consider. Frantic googling does not an expert make.

You're right about the copper core on the new model A1 - I thought it was steel entirely with thin jacket. I would argue that when, by weight, the majority of the bullet is steel, my original point still holds.

[hollerith]

I worded my original assertion the way I did (lead replaced with copper) so that it would be true even if the majority of the bullet is steel.

>I get that you're trying to be snide because you were so publicly wrong, but your tone here really just makes you sound like you're trying to sound smart

Right back at you. I don't think I'm motivated by trying to sound smart, but rather by curiosity about the subject. Well, OK, half by wanting to sound smart (and win arguments) and half by curiosity.

In particular, I'm still curious about whether ammunition containing lead is still routinely used by the US military--if you still want to talk about it. I realize Wikipedia can be totally wrong. So far I haven't succeed in wringing information out of Google Search that would corroborate or support your assertion. When's the last time you (or someone you know to usually tell the truth) has observed M855 being used by the US military in significant quantities?

[hguant]

Answering without doxxing myself is harder than I thought. The last time I was on a US military range, which to be fair was right before the pandemic so things probably have changed - we drew green tip (M855) from the range master. My understanding was that a) the steel targets were getting beat up by A1 and there wasn't any money to replace them and b) we weren't a combat group so we didn't rate the good shit.

EDIT TO ADD: I don't know if that qualifies as "quantities" and anecdotes are just that, but that's been my experience.

[hollerith]

Thanks for taking the time to set me straight on that. I didn't realizes I was posting misinformation when I wrote, "the US Army has completely stopped using lead in bullets".

[gbcfghhjj]

>The US army standard training round is the M193. It is a lead bullet jacketed with copper. Interestingly, it in many ways has better terminal performance than the M855 because this is the bullet the M16 and M4 rifles were designed around

As I understood the standard M4 with 1:7 barrel can't shoot M193 accurately