GI jacket hardness

jaysouth · December 30, 2011, 10:50 PM

I have come upon a pile of 147 gr. FMJBT bullets what were pulled down from GI ammo, 7.62, I think.

Any idea of how hard these jackets are? Harder or equal to speer/hornady/sierra jackets?

Curious about any additional wear on my barrels from shooting these bullets at moderate velocities from .30-06 or single shot .30-30.

Thanks

Missionary · December 31, 2011, 04:42 AM

Good morning
As the large manufactures are also suppliers tio the military I wouold think the jackets are about the same hardness. You can rig up a simple hardness device. Piece of tubing large enough to guide a center punch 12" down on to the side of a bullet held in place by a couple finish nails. Then measure the impact for diameter and depth. Use a standard hunting bullet & a GI.
This will be close enough for practicle info.
Mike in Peru

Marco Califo · December 31, 2011, 06:39 AM

There are three possibilities:

1. Some bullets are straight copper jacket or gilding metal (copper alloy with zinc) on lead. However, more and more military/surplus is something else, and magnetic. Copper is relatively expensive and other metals are sometimes used, even if the bullet appears to be copper colored. If a magnet will not stick, then you have copper & lead.

2. Magnetic/Not AP: Bi-metal, or, jacket containg steel under copper plate, or, cupro-nickle (Beginning around the turn of the 20th century, bullet jackets were commonly made from this material. It was soon replaced with gilding metal to reduce metal fouling in the bore.), copper flash plated onto steel jacket. Color is not an indicator. A magnet sticking to the bullet (all over) is an indicator. I do not know if these cause barrel wear. My range (on USFS land) does not allow these to be fired.

3. Magnetic/Not AP: SS-109 (5.56mm), penetrator tip, AP. These include a steel cone in the tip to pierce metal (also very effective on concrete). A magnet sticking to only the tip is an indicator. Since these are copper over lead where they touch the bore, I do not believe there is a barrel wear issue. My range (on USFS land) does not allow these to be fired.

Jim Watson · December 31, 2011, 06:42 AM

I always figured most barrel wear was hot gas erosion, not friction of copper alloy against steel. I wouldn't worry about it. Even the steel jacketed bullets are made with very mild steel, copper plated and with soft lead core, and I doubt they will accelerate wear very much.

Long ago, Phil Sharpe ran a test that convinced him not to shoot steel cored armor piercing bullets in a good barrel, but that is not the same thing.

FrankenMauser · December 31, 2011, 01:46 PM

147 gr FMJBTs are well beyond the Cupro-Nickel time period for US-made bullets. So long as they're copper-colored, I would be 100% certain they have a standard copper jacket.

So long as your bullets aren't Cupro-Nickel, they'll be fine.

jaysouth · December 31, 2011, 09:33 PM

As a digression, when I was a teenager I lived in a small southern town where it seemed almost everyone I knew was in the National Guard.

When they came back from summer camp, it seemed that they stripped their training area like locuses. Anything not nailed down was brought back. including lots of ammo.

They gave me lots of Armor piercing ammo for .30 cal MGs and M-1 garands. No one wanted to shoot it in their Model 70s because it "wore out the barrels too bad".

Well, I was glad to get and shoot it in my 1917 enfield or 1903A3. I did not worry about 'barrel wear'. Then I found out that the Armor piercing ammo had a pure copper jacket covering a tungsten carbide core. The jackets were as soft or softer than factory hunting ammo. I never said a word and continued to be the 'dumb kid' who was willing to shoot AP ammo.

I reckon over four or five years I must have shot up 3,000 rounds of it.

By the way, at short range a .30-06 AP bullet will penetrate a three foot oak tree or the web of a railroad track.

Thanks for the postings, I will load up some of the 147s next week.

December 30, 2011, 10:50 PM	#1
jaysouth Senior Member Join Date: February 27, 2001 Location: Richmond, VA Posts: 787	GI jacket hardness I have come upon a pile of 147 gr. FMJBT bullets what were pulled down from GI ammo, 7.62, I think. Any idea of how hard these jackets are? Harder or equal to speer/hornady/sierra jackets? Curious about any additional wear on my barrels from shooting these bullets at moderate velocities from .30-06 or single shot .30-30. Thanks

December 31, 2011, 06:39 AM	#3
Marco Califo Senior Member Join Date: April 4, 2011 Location: LA (Greater Los Angeles Area) Posts: 2,598	Try a magnet, too. There are three possibilities: 1. Some bullets are straight copper jacket or gilding metal (copper alloy with zinc) on lead. However, more and more military/surplus is something else, and magnetic. Copper is relatively expensive and other metals are sometimes used, even if the bullet appears to be copper colored. If a magnet will not stick, then you have copper & lead. 2. Magnetic/Not AP: Bi-metal, or, jacket containg steel under copper plate, or, cupro-nickle (Beginning around the turn of the 20th century, bullet jackets were commonly made from this material. It was soon replaced with gilding metal to reduce metal fouling in the bore.), copper flash plated onto steel jacket. Color is not an indicator. A magnet sticking to the bullet (all over) is an indicator. I do not know if these cause barrel wear. My range (on USFS land) does not allow these to be fired. 3. Magnetic/Not AP: SS-109 (5.56mm), penetrator tip, AP. These include a steel cone in the tip to pierce metal (also very effective on concrete). A magnet sticking to only the tip is an indicator. Since these are copper over lead where they touch the bore, I do not believe there is a barrel wear issue. My range (on USFS land) does not allow these to be fired. __________________ ............ Last edited by Marco Califo; December 31, 2011 at 09:58 PM. Reason: Clarity of Mud

December 31, 2011, 01:46 PM	#5
FrankenMauser Senior Member Join Date: August 25, 2008 Location: In the valley above the plain Posts: 13,424	147 gr FMJBTs are well beyond the Cupro-Nickel time period for US-made bullets. So long as they're copper-colored, I would be 100% certain they have a standard copper jacket. So long as your bullets aren't Cupro-Nickel, they'll be fine. __________________ Don't even try it. It's even worse than the internet would lead you to believe.

December 31, 2011, 04:42 AM	#2
Missionary Member Join Date: June 2, 2011 Posts: 78	Good morning As the large manufactures are also suppliers tio the military I wouold think the jackets are about the same hardness. You can rig up a simple hardness device. Piece of tubing large enough to guide a center punch 12" down on to the side of a bullet held in place by a couple finish nails. Then measure the impact for diameter and depth. Use a standard hunting bullet & a GI. This will be close enough for practicle info. Mike in Peru

December 31, 2011, 06:42 AM	#4
Jim Watson Senior Member Join Date: October 25, 2001 Location: Alabama Posts: 18,543	I always figured most barrel wear was hot gas erosion, not friction of copper alloy against steel. I wouldn't worry about it. Even the steel jacketed bullets are made with very mild steel, copper plated and with soft lead core, and I doubt they will accelerate wear very much. Long ago, Phil Sharpe ran a test that convinced him not to shoot steel cored armor piercing bullets in a good barrel, but that is not the same thing.

December 31, 2011, 09:33 PM	#6
jaysouth Senior Member Join Date: February 27, 2001 Location: Richmond, VA Posts: 787	As a digression, when I was a teenager I lived in a small southern town where it seemed almost everyone I knew was in the National Guard. When they came back from summer camp, it seemed that they stripped their training area like locuses. Anything not nailed down was brought back. including lots of ammo. They gave me lots of Armor piercing ammo for .30 cal MGs and M-1 garands. No one wanted to shoot it in their Model 70s because it "wore out the barrels too bad". Well, I was glad to get and shoot it in my 1917 enfield or 1903A3. I did not worry about 'barrel wear'. Then I found out that the Armor piercing ammo had a pure copper jacket covering a tungsten carbide core. The jackets were as soft or softer than factory hunting ammo. I never said a word and continued to be the 'dumb kid' who was willing to shoot AP ammo. I reckon over four or five years I must have shot up 3,000 rounds of it. By the way, at short range a .30-06 AP bullet will penetrate a three foot oak tree or the web of a railroad track. Thanks for the postings, I will load up some of the 147s next week.