Bullet base descriptions (with regard to jackets)

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Odd Job

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I suspect handloaders will be able to answer this best.

There are well-established descriptions for the nose of a bullet, including shape and the type of jacketing.
I want to know if there is an established way of describing the base of the bullet, with respect to the style of jacketing as it meets or covers the core. Here are four examples, all FMJ 9mm bullets:

upload_2018-10-15_12-37-0.png

Number 4 is described by some companies as "Total Metal Jacket" which is fine, but how are the other three described?
Number 1 was pulled from a PMP cartridge (Pretoria Metal Pressings)
Number 2 is from a NATO contract Hirtenberger cartridge
Number 3 is from an NGA cartridge (New Generation Ammunition)

I have various other examples, with varying degree of concavity of the base and varying degrees of coverage.

Is there an established way to describe these bullets (maybe you specify it when ordering bullets for handloading?)
 
I would call them:
1. FMJ concave base
2. FMJ flat base
3. FMJ flat base
4. TMJ

All so called “TMJ”s that I have seen personally were actually plated, not jacketed, although #4 looks like it is jacketed. Do you know who manufactured that bullet?
 
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I pulled that bullet from a cartridge with an AMT-97 headstamp. That was a small ammunition manufacturer in South Africa called Ammotech.
 
I want to know if there is an established way of describing the base of the bullet, with respect to the style of jacketing as it meets or covers the core.
Not really. While some times they describe the base, usually it isn't mentioned. Some are flat, some are concave, I have seen some that had a dimple sticking out in the middle. Any cup and core jacketed soft point or hollow point will have a solid copper base, but could be flat or concave. Any jacketed RN FMJ will have an open lead base, with the amount the jacket folds over varying, unless they do something like Hornady did with their FMJ (RN & FP) "encapsulated" bullets where they put a disc of copper on the base and the jacket gets folded over it. Plated is always completely covered, and some call it TMJ, some just say plated, the base may be flat or concave.

Lots of variety, but no real effort to describe them or designated synonyms for them like with the point of the bullet.
 
My Google-Fu hasn't turned up anything either, maybe no list exists. I've also asked on the AFTE forum, I'll let you know if they have anything to add.
As you may have guessed, my question is relevant to one of the gunshot cases from my research.
 
Do the different bases make any difference in performance?

That's a very diificult question to answer. In order to test that, you would need the same manufacturer to produce all four styles from the same materials, with the same bullet profile and jacket thickness.
Weight would be an issue also because the different styles are themselves a cause for weight differences even though these would be small.
 
There are so many different bullet design just in the full metal jacket lineup.
Here are two FMJ bullets that are totally different from each other when it comes down to the base.
This is a Federal America Eagle 115gr FMJ 9mm.
4B35D3F3-F686-469B-AC39-0BAE825ECC69.jpeg

This one is a PPU 230gr TMJ 45 ACP.
DB825E03-098C-4379-8FD1-3586BBD7AD8E.jpeg
 
There are so many different bullet design just in the full metal jacket lineup.

Agreed!
I have several trays of fired and unfired bullets in my collection and quite a few photographs of retrieved projectiles from the hospital also. Even so, there are always odd-ball examples that come up from time to time and surprise me.

I'm going to guess your 9mm was fired from a Glock and the .45 from a Colt 1911.
 
Agreed!
I have several trays of fired and unfired bullets in my collection and quite a few photographs of retrieved projectiles from the hospital also. Even so, there are always odd-ball examples that come up from time to time and surprise me.

I'm going to guess your 9mm was fired from a Glock and the .45 from a Colt 1911.
You got one right. The 9mm was from a Gen3 Glock 17 anf the 45 was from a Hi-Point. The Hi-Point has more lands and groves.
 
I took a long reach on that .45 because I was looking for a common .45 with a left hand twist. The Glock rifling is very obvious though.
 
Montana Gold makes CMJ (Complete Metal Jacket) they simply drop a small copper/brass disk onto the lead core before the final strike. If you go to a USPSA/IDPA match with a lot of steel targets and alot of competitors shooting MG CMJ ammo those little disks will be all around the steel.

9mm_124_cmj_back_1.jpg
 
That is the same way Hornady did their "encapsulated" FMJ bullets.

index.php
 
I would call them with following additional descriptions:

1. FMJ - Concave or "dished" lead base
2. FMJ - Flat lead base with lip
3. FMJ - Flat lead base
4. Plated RN - Solid base (or TMJ if bullet is verified to be trademarked Speer TMJ)


1. FMJ - Concave or "dished" lead base

FMJ with flat lead base pushed in to form a concave cavity done to help expand bullet base to better seal with barrel and reduce gas leakage around the bullet.

Hollow Base - If the cavity is deep enough, bullet will become "Hollow Base" as shown below left that also increases the length of bullet base/bearing surface to improve neck tension (same intent as Berry's Hollow Base RN on the right) and better engage the rifling (reasons why 124 gr FMJ/RN bullets are favored over 115 gr FMJ/RN with shorter base for accuracy). So with 115 gr HB FMJ/RN, you end up with similar bullet base length as 124 gr FMJ/RN. Notice both hollow base bullets are longer/taller compared to solid base bullet in the center.

full&d=1539630388.jpg

Here's Federal (.FC. headstamp) 9mm 115 gr FMJ pulled to show hollow base bullet - https://www.thehighroad.org/index.php?threads/factory-rounds-pulled.706260/

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2. FMJ - Flat lead base with lip

FMJ flat lead base with jacket that forms a "lip" around the base. Winchester 115 gr FMJ shown below right shows more defined lip around the base. The "lip" may have been intended to form a concave or dished base to better trap expanding gas to better expand the bullet base to seal with the barrel.

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3. FMJ - Flat lead base - FMJ with exposed lead base.

Here's Remington (RP headstamp) 9mm 115 gr FMJ pulled to show flat lead base - https://www.thehighroad.org/index.php?threads/factory-rounds-pulled.706260/

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4. Plated RN - Solid base (or TMJ if bullet is verified to be Speer TMJ)
Number 4 is described by some companies as "Total Metal Jacket"
4. TMJ

All so called “TMJ”s that I have seen personally were actually plated, not jacketed ... Do you know who manufactured that bullet?
I pulled that bullet from a cartridge with an AMT-97 headstamp. That was a small ammunition manufacturer in South Africa called Ammotech.
Bullet number 4 definitely looks plated. If the ammunition came from South Africa, plated bullet used could have been made by Frontier Bullets/FMP Bullets (Frontier Metal Processing), which is also based in South Africa - https://fmp-bullets.com/collections/cmj-bullets
Frontier Bullets said:
Bullets are completely coated in pure copper ... plated bullet


As to TMJ (Total Metal Jacket), it is trademarked originally by Alliant Techsystems Inc. (Now Vista Outdoor) - https://trademarks.justia.com/738/33/tmj-73833272.html

TMJ bullets are "thick plated" and I believe originally intended to produce projectiles with no exposed lead to reduce lead exposure (supplemented by use of non-toxic primers) but as demonstrated by Gold Dot HP bullets (which are even thicker plated bullets), showed no jacket separation from lead core that some other JHP bullets suffered. TMJ, as best as I can find have around .015" thickness copper plating which is around the thickness of gilding metal used for jacketed bullets (which is around .015"-.030" in thickness) - https://www.thehighroad.org/index.p...ng-at-25-50-yards.808446/page-3#post-10470195

TMJ bullets are sold by Speer in bulk and also used to manufacture factory ammunition - https://www.speer-ammo.com/en/bulle...ndgun-plinking-bullets/355/355-115-tmj-bullet

Here's Blazer (BLAZER headstamp) 9mm 124 gr "FMJ" pulled to show solid copper plated base - https://www.thehighroad.org/index.php?threads/factory-rounds-pulled.706260/

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Speer TMJ bullets could be used by other manufactures to produce "FMJ" ammunition. Here's Remington 45ACP 230 gr "FMJ" pulled to show solid copper plated base - https://www.thehighroad.org/index.php?threads/factory-rounds-pulled.706260/#post-8782418

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Thanks BDS that is very useful!
I have been calling those bullets a mixture of dish-shaped or concave base and it seems there is no better term.
 
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