I’ve always heard this term. I’ve been shooting for almost 20 years now, but guess I was maybe embarassed to ask someone face-to-face. So what is it? I currently have been shooting my M-1 carbine with either American Federal loads, or Winchester x30M1 hollow-points. Do they count? If now, why are they different than FMJ’s and how so?
A full metal jacketed bullet is exactly that- a lead core completely encased in metal. A hollowpoint has an exposed core for purposes of expansion.
I was hoping you’d show up for this one, I knew you’d have answer. I thought the American Federal’s I shoot for target practice were FMJ’s, just not sure. Thanks for the link.
Pardon my nit picking but that is incorrect about nearly all bullets labelled FMJ such as found in military rifle and handgun ball ammunition. All of the ones I have seen have an exposed lead base which isn’t obvious in loaded ammunition. The jacket is drawn from the front but is not closed at the base.
The only bullets I have seen that are totally covered in copper are usually plated lead bullets labelled as TMJ for total metal jacket. The copper coating is somewhat thinner than the drawn metal jackets.
I’m not aware of any spitzer type rifle bullets which have a truly continuous, unbroken copper jacket. Some have the jacket drawn from the base so there is no exposed lead there but the tip is either hollow with the lead core exposed a fraction of an inch inside or with a plastic tip covering the end. Note that those hollowpoint bullets are not so much for expansion as for more accurate flight.
I forgot to mention all the TMJ or plated bullets I have seen are for handgun ammunition. .30 carbine is in kind of a twilight zone beause the cartridge has more in common with handgun ammunition than most typical rifle ammunition.
My .30 M1 is the same as the US military issued (though the SDMB has confirmed it’s a replica at best) but still it’s an M1 for all intents and purposes. Now, the only way to know what’s on the butt end of the bullet is to somehow capture it, which I don’t know how to do accurately. I guess a better question is, does Winchester or American Federal make a FMJ? If not, can one be bought outside the military or am I taking my chances?
Duffer, my point was that the bullets everyone, including me, call full metal jacket really aren’t when you get really persnickety about terminology.
I’m not certain exactly what you’re asking with the line “do they count?” in the OP so I’m going to read between the lines a bit.
You will not harm your M1 by firing *SAAMI spec ammunition be it full metal jacket or hollowpoint so no worries.
The military specifies FMJ ammunition because the harder copper nose is less likely to deform which helps it feed smoothly through a weapon’s action. Some folks intrepret the Hague Accord as prohibiting the military from using anything but FMJ but this not true IMO and debatable at best.
The other reason for a copper jacket is that copper will leave less metal deposited in the bore than lead. If a lead bullet is pushed to high velocity it will actually smear like peanut butter in the bore. This not only destroys accuracy but in rifles could cause potentially dangerous high pressures. Lead bullets can be used in rifles but they are typically loaded for reduced velocities.
*Sporting Arms and Ammunition Manufacturer’s Institute - a trade group that establishes technical standards for ammunition.
Which explains why I always have to fire some copper-jacketed .357 rounds out of my magnum after a session of .38 wadcutters to clean all of that darned peanut butter out. I guess that those .38s aren’t really going “high velocity,” so I shudder at the thought of the mess that lead rifle bullets must leave behind in the barrel.
I actually used to do that too but I’ve been told not to. Some folks say instead of pushing the lead out it just burnishes it against the rifling and makes it harder to remove. Lead alloy and lubrication make a huge difference. I only use pure lead in black powder cap and ball revolvers. For cartridges I use bullets made from a lead alloy that has 2% tin and 6% antimony that have a big lube groove and I don’t have any leading problems.