Post by revolvercranker on Jan 8, 2024 11:54:28 GMT -5
As suggested by David Bradshaw I'm reposting this Cartridge Brass article here.
"Cartridge Brass"
Cartridge brass can vary from 67/33 to 72/28 Copper Zinc alloy, with most brass being "70/30"
The Germans set on the 67/33 mix very early on,( 1880s) for use in all types of Firearms; but during WW II, the 72/28 mix was used for some Aviation Ammunition, due to its better hardness factors.
Hardness of brass:
The sheet (coil) which is "Punched and cupped" is normally "Half Hard" grade; after this first operation, they are Tumble annealed in a rotary kiln furnace, to "dead soft", Pickled, washed and lubricated for the "deep draw" operations (up to four draws for a long rifle case, such as .30/06. )
Draws can be single or double ( two dies in tandem). Annealing occurs usually at draw 2 and 4.
Differential hardness.
This is achieved by the "Heading" process, to form the head and primer Pocket, which, depending on Country usage, can be several operations or just one. British (,303) cases were usually "Indented" (rough formed Primer Pocket and Berdan Anvil) then "Headed" ( head flattened, Rim formed) and then "Bunted" ( primer pocket given final dimensions, headstamp applied.)
All these separate operations successively hardened the head around the Primer Pocket, so that the Head overall is about twice the hardness of the shoulder.
With the tapering of the case, and the forming of the shoulder and neck, the case further hardens, and so the final "Neck and shoulder anneal" softens the area which needs to expand on firing (yet still grip the bullet until it does so.)
It was only during andf after WW I that US Ammo makers realised what Russian and other European Makers had already known...that the After-neck form Anneal was essential to prevent "age cracking or season cracking" in ammo, at least in the medium term...US-made .30 cal in WW I had a bad habit of cracking after about 3-5 years, rendering Billions of WW I production virtually useless except for single load training in Bolt rifles (1920s ands 30s)
The same happened to US-made .303 British sent to UK in 1915-1918...at war's end, most was either dumped in the North Sea ( bad Powder(Dupont) also contributed) or given away to Portugal or the Baltic States.
The Portuguese eventually dismantled all the US-made .303 in the late 20s, and recycled the projectiles into cases made by their own Arsenal.(AE 1928)
The Russian Inspectors at Western Cartridge, in 1916, insisted on the "post necking" anneal, and the "leaving the heat marks" on the neck and shoulder as proof that the anneal had been done...a feature only adopted by US Ordnance in the mid to late 1920s....
AS to Lathe turning, there are two operations during cartridge making which could be called "Turning"...the final head dimensions ( rim profile and extractor groove profile) are all done by a Lathe type operation, with form cutters. The trim-to-length machine, also uses either a Knife cutter (European type) or a Milling Cutter (BlackRock USA) type.
Some Fritz Werner Trimmers do both Head and OAL cutting in one chuck and one operation.
Italian cases ( 6,5x52 Carcano) also had the neck reamed internally to provide a Positive stop for Bullet seating.
Further to Case-head hardening, Italian M1891 cases were modified in 1895, by adding a further ring indentation in the head, which added further hardness to the head, and also acted as a "self sealing" crimp on the moment of firing. This design feature was used by the French in the Pointed 8mm Lebel (M1898--"Balle D") to avoid "bullet -primer" ignition" in the Tube loaded Lebel Rifle (the groove caught the bullet point away from the Primer) and also aided primer seal in the heavy firing Hotchkiss MG.
The French continued this design feature in the 1924/29 7,5mm cartridge, copying the US ANM2 aircraft .30 cal round of 1918 ( made by USCCo.) --Distinguishable by its Indented ring in the head, as well as multiple stab/staked crimps.
Aircraft MG ammo was liable to jamming if primers shifted during firing, and it was almost impossible to "Clear" a jammed gun in flight. Hence the Harder heads, and heavily crimped Primers...in fact, the French, having acquired US made .303 ammo from Britain along with (Aircraft) Lewis Guns,( 1915-16) dismantled the ammo, "re-crimped" the primers (by adding three or four "stakes") and reloaded the cases with tracer projectiles ( also acquired from Britain; before beginning production themselves.).
During the 1930s, Germany advanced Cartridge brass technology by using different alloys for different purposes ( Aviation, High rate of fire guns, etc) before developing Steel case technology ( started in 1917) through several methods of Drawing and coating the raw steel during and after manufacture.
The Russians also had parallel developments, utilising Copper-clad steel. To be noted that whilst the copper-clad mild steel was a German WW I development, the German WW II Phosphatised steel case ("Bonderisation") was originally a French patent which was not pursued by the French....but avidly used from 1941 to 45 by the Germans, and by the Czechs since 1945 onwards.... Phosphatised (aka US Parkerised) steel cases are still the most cost effective of the Various Steel and Brass manufacturing processes for cartridge case making. The French did make Ammo in the 1950s with the "Bonderisation steel case process" ( all the US calibres, plus 7,5 M24/29.
Back in 1918, the Hooker Chemical Co. (USA) did patent an "Impact Extrusion" process for case making; it worked well for eventually making Beer cans and Soda cans, both in Steel and Aluminium (some 40 years later); but small trial lots of Brass .30 cal cases were a dismal failure, both at firing ( split cases) and the expense of forming tools. ( USCCo made the cases).
AS to making your own cases from rod, by Lathe turning, this was first done in the 1880s, with "Everlasting" cases, either fully brass, or a steel head with a brass body threaded on...best used for straight bodied cases for Black Powder. With the introduction of Bottlenecked cases and smokeless Powders, case life of this turned type dropped off quickly. Even today, one finds only Antique BP case being made by Turning; furthermore, the neck and shoulder (if there is one) has to be annealled to prevent splitting, and the head is usually hardend somewhat by Hammering a suitable headstamp into it...and making the Primer Pockets a flea's whisker undersized, to prevent primer leakage in "half-hard" heads. (The primer is a real "press fit.")
I have some "Turned and sized" 13x92SR Mauser T1918 AT Rifle cases, they seem to be holding up quite well ( primers are US .50 cal type)...But I can make them equally well from .50BMG cases without having a semi rim (extractor is sufficient.)
Anyway, enough guff about "Cartridge brass".
Doc AV
AV Ballistics Film Ordnance Services (other "ordnance" as well)
Brisbane Australia.
"Cartridge Brass"
Cartridge brass can vary from 67/33 to 72/28 Copper Zinc alloy, with most brass being "70/30"
The Germans set on the 67/33 mix very early on,( 1880s) for use in all types of Firearms; but during WW II, the 72/28 mix was used for some Aviation Ammunition, due to its better hardness factors.
Hardness of brass:
The sheet (coil) which is "Punched and cupped" is normally "Half Hard" grade; after this first operation, they are Tumble annealed in a rotary kiln furnace, to "dead soft", Pickled, washed and lubricated for the "deep draw" operations (up to four draws for a long rifle case, such as .30/06. )
Draws can be single or double ( two dies in tandem). Annealing occurs usually at draw 2 and 4.
Differential hardness.
This is achieved by the "Heading" process, to form the head and primer Pocket, which, depending on Country usage, can be several operations or just one. British (,303) cases were usually "Indented" (rough formed Primer Pocket and Berdan Anvil) then "Headed" ( head flattened, Rim formed) and then "Bunted" ( primer pocket given final dimensions, headstamp applied.)
All these separate operations successively hardened the head around the Primer Pocket, so that the Head overall is about twice the hardness of the shoulder.
With the tapering of the case, and the forming of the shoulder and neck, the case further hardens, and so the final "Neck and shoulder anneal" softens the area which needs to expand on firing (yet still grip the bullet until it does so.)
It was only during andf after WW I that US Ammo makers realised what Russian and other European Makers had already known...that the After-neck form Anneal was essential to prevent "age cracking or season cracking" in ammo, at least in the medium term...US-made .30 cal in WW I had a bad habit of cracking after about 3-5 years, rendering Billions of WW I production virtually useless except for single load training in Bolt rifles (1920s ands 30s)
The same happened to US-made .303 British sent to UK in 1915-1918...at war's end, most was either dumped in the North Sea ( bad Powder(Dupont) also contributed) or given away to Portugal or the Baltic States.
The Portuguese eventually dismantled all the US-made .303 in the late 20s, and recycled the projectiles into cases made by their own Arsenal.(AE 1928)
The Russian Inspectors at Western Cartridge, in 1916, insisted on the "post necking" anneal, and the "leaving the heat marks" on the neck and shoulder as proof that the anneal had been done...a feature only adopted by US Ordnance in the mid to late 1920s....
AS to Lathe turning, there are two operations during cartridge making which could be called "Turning"...the final head dimensions ( rim profile and extractor groove profile) are all done by a Lathe type operation, with form cutters. The trim-to-length machine, also uses either a Knife cutter (European type) or a Milling Cutter (BlackRock USA) type.
Some Fritz Werner Trimmers do both Head and OAL cutting in one chuck and one operation.
Italian cases ( 6,5x52 Carcano) also had the neck reamed internally to provide a Positive stop for Bullet seating.
Further to Case-head hardening, Italian M1891 cases were modified in 1895, by adding a further ring indentation in the head, which added further hardness to the head, and also acted as a "self sealing" crimp on the moment of firing. This design feature was used by the French in the Pointed 8mm Lebel (M1898--"Balle D") to avoid "bullet -primer" ignition" in the Tube loaded Lebel Rifle (the groove caught the bullet point away from the Primer) and also aided primer seal in the heavy firing Hotchkiss MG.
The French continued this design feature in the 1924/29 7,5mm cartridge, copying the US ANM2 aircraft .30 cal round of 1918 ( made by USCCo.) --Distinguishable by its Indented ring in the head, as well as multiple stab/staked crimps.
Aircraft MG ammo was liable to jamming if primers shifted during firing, and it was almost impossible to "Clear" a jammed gun in flight. Hence the Harder heads, and heavily crimped Primers...in fact, the French, having acquired US made .303 ammo from Britain along with (Aircraft) Lewis Guns,( 1915-16) dismantled the ammo, "re-crimped" the primers (by adding three or four "stakes") and reloaded the cases with tracer projectiles ( also acquired from Britain; before beginning production themselves.).
During the 1930s, Germany advanced Cartridge brass technology by using different alloys for different purposes ( Aviation, High rate of fire guns, etc) before developing Steel case technology ( started in 1917) through several methods of Drawing and coating the raw steel during and after manufacture.
The Russians also had parallel developments, utilising Copper-clad steel. To be noted that whilst the copper-clad mild steel was a German WW I development, the German WW II Phosphatised steel case ("Bonderisation") was originally a French patent which was not pursued by the French....but avidly used from 1941 to 45 by the Germans, and by the Czechs since 1945 onwards.... Phosphatised (aka US Parkerised) steel cases are still the most cost effective of the Various Steel and Brass manufacturing processes for cartridge case making. The French did make Ammo in the 1950s with the "Bonderisation steel case process" ( all the US calibres, plus 7,5 M24/29.
Back in 1918, the Hooker Chemical Co. (USA) did patent an "Impact Extrusion" process for case making; it worked well for eventually making Beer cans and Soda cans, both in Steel and Aluminium (some 40 years later); but small trial lots of Brass .30 cal cases were a dismal failure, both at firing ( split cases) and the expense of forming tools. ( USCCo made the cases).
AS to making your own cases from rod, by Lathe turning, this was first done in the 1880s, with "Everlasting" cases, either fully brass, or a steel head with a brass body threaded on...best used for straight bodied cases for Black Powder. With the introduction of Bottlenecked cases and smokeless Powders, case life of this turned type dropped off quickly. Even today, one finds only Antique BP case being made by Turning; furthermore, the neck and shoulder (if there is one) has to be annealled to prevent splitting, and the head is usually hardend somewhat by Hammering a suitable headstamp into it...and making the Primer Pockets a flea's whisker undersized, to prevent primer leakage in "half-hard" heads. (The primer is a real "press fit.")
I have some "Turned and sized" 13x92SR Mauser T1918 AT Rifle cases, they seem to be holding up quite well ( primers are US .50 cal type)...But I can make them equally well from .50BMG cases without having a semi rim (extractor is sufficient.)
Anyway, enough guff about "Cartridge brass".
Doc AV
AV Ballistics Film Ordnance Services (other "ordnance" as well)
Brisbane Australia.