Have you found bullets get softer as they age?

Grumpy gumpy said:

Michael, you know copper and brass age harden and become brittle…….


Like anything, they don’t go off if you use them first
Gumpy

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• Neither pure copper nor pure lead nor brass (copper/zinc alloy) soften or harden over time. Copper and brass “work harden” if physically worked, but can be softened again if heated to over 500 deg F (annealing). They will not harden or soften if their physical form is not changed or if not subjected to enough heat. Pure lead does not work harden or soften.
• When dissimilar metals are placed in physical contact (bullet jackets and cores), they can be subject to a process called “galvanic corrosion” over time. This process can be accelerated depending on the presence of electrolytes like chlorides (salts), low Ph (acids), heat, or electrical current. Condensation constantly forming and reforming on metal objects in humid and/or saltwater climates can significantly accelerate galvanic corrosion. Other VERY significant properties that can effect extent and rate of galvanic corrosion include relative “nobility” of the 2 metals involved, the total surface area of metals involved, AND EXTENDED PERIODS OF TIME.
• Tin and copper have a special chemical “affinity” for each other. This is utilized for “tinning” copper cookware and tin is sometimes used in soldering copper. "Tinning" has been used to bond bullets and jackets. This tin copper bond can also occur to some degree if a core with high tin content is heat bonded to a jacket without “tinning”, and could even take place in a cold bond over time. When tin and copper come in contact at high temperature, they don’t just bond directly, they specifically create 2 “intermetal” layers. Copper is chemical element Cu. Tin is chemical element Sn. Bronze is the ALLOY of copper and tin melted together, CuSn. If you put melted tin in contact with hot solid copper, 2 intermetal layers are formed that bind the copper and tin together. A Cu3Sn ionized layer next to the copper, bound to a Cu6Sn5 ionized layer bonded to the tin, and the 2 ionized intermetals bonded to each other. HOWEVER, OVER EXTENDED TIME, THE Cu3Sn LAYER CONSUMES THE Cu6Sn5 LAYER, LEAVING A VERY HARD/BRITTLE INTERMETAL BONDED TO THE COPPER, AND IN PLACE OF THE Cu6Sn5 LAYER IS AN OXIDATION PRODUCT THAT COULD WEAKEN CONTACT WITH THE TIN.

• If a bullet is created with a copper clad steel jacket, over time the copper (medium noble) on the outside and the lead (medium noble) on the inside will draw electrons out of the steel (low noble) , causing the steel to oxidize and weaken through the process of galvanic corrosion. This is what older Kynoch bullets suffered from after a couple decades that completely compromised the bullet. If bullets have steel jackets in contact with copper and/or lead, USE EXTREME CAUTION DECIDING WHETHER OR NOT TO USE THESE BULLETS ON DANGEROUS GAME IF MORE THAN A YEAR OR TWO OLD.
• If a bullet is created with a copper jacket or predominantly copper alloy (gilding metal or yellow brass or red brass) that was bonded with tin, or bonded to a lead alloy core with significant amount of tin in it as a hardener, USE EXTREME CAUTION DECIDING WHETHER OR NOT TO USE THESE BULLETS ON DANGEROUS GAME IF MORE THAN A YEAR OR TWO OLD.
• If you do not know the exact chemical makeup of the jacket and the core of the bullet, or the chemical bonding process, or do not have reliable data on performance of these bullets regardless of age, USE EXTREME CAUTION DECIDING WHETHER OR NOT TO USE THESE BULLETS ON DANGEROUS GAME IF MORE THAN A YEAR OR TWO OLD.

AJ Peacock said:

Yes, I've experienced that with lead alloy bullets. If the core of a jacketed bullet has antimony and is hardened, it will also soften. The following is from AI.

Pure lead doesn't get softer with age; it remains highly malleable. However, lead alloys (like those with antimony or calcium) undergo "age softening". This happens when heat-treated, rapidly cooled alloys slowly release trapped atoms over years, causing stiff crystalline structures to degrade and revert to a softer state.

AJ

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coreydb said:

Bullets don't get softer with age. Lead is an element and the copper alloys aren't soft either. I've shot 60 year old ammo (7.62/.308) that maintained tight groups at 100 yds. Other things can come into play that can affect the ammo over the decades. Corrosion from improper storage, old powder diminishing velocity, poor bullet seating that allows moisture inside.....

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mgstucson said:

As an amateur bullet maker, I have had to learn some important facts about properties of certain metals, certain metal alloys, and certain chemical phenomena of dissimilar metal contact.

Metallurgy facts:

• Neither pure copper nor pure lead nor brass (copper/zinc alloy) soften or harden over time. Copper and brass “work harden” if physically worked, but can be softened again if heated to over 500 deg F (annealing). They will not harden or soften if their physical form is not changed or if not subjected to enough heat. Pure lead does not work harden or soften.
• When dissimilar metals are placed in physical contact (bullet jackets and cores), they can be subject to a process called “galvanic corrosion” over time. This process can be accelerated depending on the presence of electrolytes like chlorides (salts), low Ph (acids), heat, or electrical current. Condensation constantly forming and reforming on metal objects in humid and/or saltwater climates can significantly accelerate galvanic corrosion. Other VERY significant properties that can effect extent and rate of galvanic corrosion include relative “nobility” of the 2 metals involved, the total surface area of metals involved, AND EXTENDED PERIODS OF TIME.
• Tin and copper have a special chemical “affinity” for each other. This is utilized for “tinning” copper cookware and tin is sometimes used in soldering copper. "Tinning" has been used to bond bullets and jackets. This tin copper bond can also occur to some degree if a core with high tin content is heat bonded to a jacket without “tinning”, and could even take place in a cold bond over time. When tin and copper come in contact at high temperature, they don’t just bond directly, they specifically create 2 “intermetal” layers. Copper is chemical element Cu. Tin is chemical element Sn. Bronze is the ALLOY of copper and tin melted together, CuSn. If you put melted tin in contact with hot solid copper, 2 intermetal layers are formed that bind the copper and tin together. A Cu3Sn ionized layer next to the copper, bound to a Cu6Sn5 ionized layer bonded to the tin, and the 2 ionized intermetals bonded to each other. HOWEVER, OVER EXTENDED TIME, THE Cu3Sn LAYER CONSUMES THE Cu6Sn5 LAYER, LEAVING A VERY HARD/BRITTLE INTERMETAL BONDED TO THE COPPER, AND IN PLACE OF THE Cu6Sn5 LAYER IS AN OXIDATION PRODUCT THAT COULD WEAKEN CONTACT WITH THE TIN.

This article about tinning cookware actually has microscopic photos of these layers and other explanations and illustrations.

What Lies Behind the Tin Lining Copper Pans?: The Chemistry Behind the Bond

Effects On Bullets Over Time

• If a bullet is created with a copper clad steel jacket, over time the copper (medium noble) on the outside and the lead (medium noble) on the inside will draw electrons out of the steel (low noble) , causing the steel to oxidize and weaken through the process of galvanic corrosion. This is what older Kynoch bullets suffered from after a couple decades that completely compromised the bullet. If bullets have steel jackets in contact with copper and/or lead, USE EXTREME CAUTION DECIDING WHETHER OR NOT TO USE THESE BULLETS ON DANGEROUS GAME IF MORE THAN A YEAR OR TWO OLD.
• If a bullet is created with a copper jacket or predominantly copper alloy (gilding metal or yellow brass or red brass) that was bonded with tin, or bonded to a lead alloy core with significant amount of tin in it as a hardener, USE EXTREME CAUTION DECIDING WHETHER OR NOT TO USE THESE BULLETS ON DANGEROUS GAME IF MORE THAN A YEAR OR TWO OLD.
• If you do not know the exact chemical makeup of the jacket and the core of the bullet, or the chemical bonding process, or do not have reliable data on performance of these bullets regardless of age, USE EXTREME CAUTION DECIDING WHETHER OR NOT TO USE THESE BULLETS ON DANGEROUS GAME IF MORE THAN A YEAR OR TWO OLD.

Cartridge manufacturers have access to all info necessary to make theses determinations and should stamp the case heads with a 2 digit year of manufacture (like Lake City military brass) and warnings about when to take the bullets out of service for dangerous game. They probably will when some marketing genius figures out it will increase sales and brand loyalty at the same time.

View attachment 773943

Bullets could be stamped with dates like this.

(20+) Video | Facebook

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grand veneur said:

That is certainly something to consider; however, I find the timeframe in which the bullets are said to begin changing to be rather short. It is not unusual to use somewhat older ammunition, factory loads above all, even when hunting dangerous game. While the process may exist, it is in my opinion likely of little practical relevance with this ammunition. I myself have frequently used factory loads that were decades old, among other things for buffalo hunting, and have also loaded cartridges using older bullets for the same purpose. I must admit that with old 10,75x68 cartridges, factory loads from RWS, I experienced the classic steel-jacketed bullets completely disintegrating inside the body of all buffalo that I shot with. At the time I attributed this to the thin steel jackets of those classic FMJ bullets. Perhaps there was something else at play after all.

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Kootenay Hunter said:

Hello All,

This question came to me as I was looking for bullet recommendations for a new (to me) caliber. The rifle is an old Mauser that looks like it was reworked by JGA (Anschutz) into a 9.3x57. There is not a lot of load data on that caliber so I was looking through the ballistic studies website, as he usually gives pretty good recommendations on bullet performance vs impact speed.
So there I was on the 9.3x62 page, examining what he had to say about commonly available 9.3mm pills, and what velocities they would work at (knowing that the 9.3x57 would be around 200fps slower than the x62), when I came across this paragraph:

View attachment 772738

Generally our hunting projectiles are copper alloys and lead alloys, and while they will develop surface oxides, their hardness should remain relatively unchanged. Have any of you found that older bullets have difference performance compared to when they were new?
Is he maybe just getting mixed up due to different batches acting differently?
Is this Ea-nāṣir, spiting us from beyond the grave?

Here is the page I found it on, it is in the section on the speer 270gr hotcor: www.ballisticstudies.com/Knowledgebase/9.3x62.html

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Journey said:

Haha AI is a inconsistent mistress. Here's what I got.

Lead alloys: can harden over time, especially if they contain antimony; that’s why cast bullets made from alloy can become harder after casting �.

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AJ Peacock said:

I've personally experienced softening over time on Antimony alloyed lead, regardless of the fickle AI mistress.

AJ

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Journey said:

View attachment 772753

This is a "old" (probably ~30 years) 250 grain nosler partition out of a 338 win mag that went thru 2 bull elk shoulders at ~50 yards and was just under the skin on the far side. Always thought it was a tad strange how much mass was lost since the bullet wasnt traveling that fast (~2650fps). Lead softening could explain this.

Thx AJ

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