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Author Topic: Jacket Styles (Bullet Base)  (Read 3053 times)

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Offline Brandon Bertolli

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Jacket Styles (Bullet Base)
« on: October 15, 2018, 07:17:52 AM »
Is there a list of jacket styles when it comes to the base of the bullet? For example, take these four 9mm bullets:


31383-0


They all have a varying degree of protrusion or coverage at the base. These can have different radiographic appearances which is why I am interested in them.


1 = from a PMP cartridge (Pretoria Metal Pressings)
2 = from a Hirtenberger cartridge (NATO contract)
3 = from an NGA cartridge (New Generation Ammunition)
4 = from an AmmoTech cartridge (AMT-97 headstamp)
Brandon Bertolli, Radiographer, bbertolli(at)yahoo.com

Offline Eric Warren

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Re: Jacket Styles (Bullet Base)
« Reply #1 on: October 15, 2018, 08:59:29 AM »
Just based on jacket style, I would not distinguish between the first 3 bullets - I would call them all FMJ.  The 4th bullet I would call a TMJ.

Offline Brandon Bertolli

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Re: Jacket Styles (Bullet Base)
« Reply #2 on: October 15, 2018, 01:20:03 PM »
Thanks Eric. I have heard TMJ used before and that makes sense.
The other three bullets need differentiation even if I have to simply describe each one as seen, because appearances may differ radiologically.


That Hirtenberger has an almost rolled lip appearance where the jacket sits proud of the core at the base. The NGA base is flush and the PMP is concave.
I have various bullets in my collection with various degrees of concavity, from deep to shallow.
It seems there is quite a lot of variation to be seen even when looking at just 9mm bullets.


Brandon Bertolli, Radiographer, bbertolli(at)yahoo.com

Offline Steve Scott

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Re: Jacket Styles (Bullet Base)
« Reply #3 on: October 16, 2018, 08:44:31 AM »
No surprise, I agree with Eric's assessment of the bullets.  Once fired, I doubt the subtle differences between #2 and #3 would be noticeable.
Steve Scott

Offline Mark Tanner

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Re: Jacket Styles (Bullet Base)
« Reply #4 on: October 16, 2018, 01:20:47 PM »
I agree with Eric, but if you want to take it a step further this is what I would say.


1. Open concave base - FMJ
2. Open recessed base - FMJ
3. Open flat base - FMJ
3. Closed flat base -TMJ

Offline Zak Carr

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Re: Jacket Styles (Bullet Base)
« Reply #5 on: October 17, 2018, 09:09:02 AM »
If memory serves me, I believe that Axel categorizes base types by the subtle design differences in CartWin Pro.  Since switching agencies, I no longer have access to it though.
Zak.
Zak Carr
Johnson County Sheriff's Office Criminalistics Laboratory
Firearm and Toolmark Section
zachary.carr@jocogov.org

Offline Aaron Brudenell

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Re: Jacket Styles (Bullet Base)
« Reply #6 on: October 17, 2018, 05:50:13 PM »
Check out the Winchester USA brand 115 grain 9mm and the 110 grain 357 Mag--both have deeper concave bases than your examples and may provide additional radiographic distinctions.
Aaron Brudenell
Firearm Examiner
Arizona Dept. of Public Safety
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Offline Brandon Bertolli

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Re: Jacket Styles (Bullet Base)
« Reply #7 on: October 18, 2018, 03:57:26 AM »
Thanks all, this has been very helpful!
Rather than reinvent the wheel I would like to use terminology that is in use currently, and if Axel Manthei has a list I would look at it first.

Steve Scott said:

Quote
Once fired, I doubt the subtle differences between #2 and #3 would be noticeable.


It may not be obvious in the photo but number 2 has an almost roll-like protrusion of the jacket from the core which makes it more readily visible on a radiograph. Granted, my radiographs of those four bullets are in the unfired state. I don't have many pairs of unfired and fired FMJs in my collection, to compare the bases. But I take the point, there might be differences on firing.

If someone has examples of differences concerning FMJs fired vs unfired I would be interested in seeing them! Is there a core swaging effect in some instances?











Brandon Bertolli, Radiographer, bbertolli(at)yahoo.com

 

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