Full Metal Jacket?

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47CubPilot

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I've only been shooting for 41 years, so I'm a relative novice.
I recently purchased my first 1911 style handgun (Colt 1991A1 Commander). Last Sunday I put 150 rounds of Federal Champion thru it, with absolutely no problems. :D
I was firing into a very large pile of snow. With the warm weather in N. central IL this week the snow has really melted. Because of this, I was able to recover 102 of the bullets today.
I always thought that a FMJ was completely enclosed, and a jacketed bullet had an exposed base.
Well, 101 were like the one on the right, and 1 was the one on the left.
Have I been misinformed all these years?
 

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As far as I know jacketed has a couple meanings, FMJ means the opening is in the base, whereas, jacketed can mean there may be a hollow point or exposed lead and the base is enclosed. FMJ is required for military bullets, soft point or hollow point is required for most hunting. It is not practical to fully enclose the core, there are exceptions but most mass produced bullets are open at one end.
 
FMJ (also called "ball") has an exposed base. The term "full" is misleading. The outer jacket starts out as a cup of copper, brass, or "gilding" metal and is "drawn" or formed over the lead core. JHP, jacketed hollow point, JSP and OTM have the jacket drawn over the lead core as well, but with the opening on the tip of the bullet.

TMJ, "total" metal jacket, or plated, covers the whole bullet.
 
Any jacketed bullet must have a opening ether front or rear, as part of the manufacturing process. If it doesn't have a opening, it's plated not jacketed.
 
As already explained a lead core is swaged into a copper cup.
If the base of the cup is at the rear, you have a SP or HP bullet with a closed base, and an open point with lead exposed at the front.

If the core is swaged in the jacket cup from the rear, you have a FMJ with lead exposed at the base.

Then it gets more complicated.

Some FMJ bullets are made with a disk covering the exposed lead in the base and crimped in place as the bullet is swaged. Sometimes called an Encapulated bullet, or FMJ EC.
It's still a FMJ.

Then you have Plated bullets such as the Speer Gold Dot, Berry plated bullets, and others.
In these, the jacket is electroplated on the lead core, and has no opening, unless they swage a HP cavity in the end, as on the Speer Gold Dot HP.
That's how they got the name.

The Gold Dot at the bottom of the HP cavity is the remains of the FMJ plating pushed into the bottom of the HP cavity by the swaging punch that forms the HP.

But back to the question.
Most military FMJ bullets have the lead core exposed in the base, just as yours do.

The one on the right is a FMJ cup & core bullet.
The one on the left is an electroplated jacket bullet.
(Probably the only one you found from the aluminum case Federal stuff.)

rc
 
I had heard once I think the term total metal jacket to indicate the base of the bullet was also encased in copper.
 
+1. You see "total metal jacket" sometimes. Relatively recent innovation since lead in bullets has become an environmental football in some places.
 
alexander45
The snow that I was shooting into was what I had piled up. I was shooting into the long axis of a pile that was about 40 feet long, 15 feet wide and 8 feet deep. With a hill behind it, and nothing for over a mile beyond that.
The bullets seem to have penetrated approximately 2 to 3 feet.
They are in a neat little pile. :D
 
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