Square flake powder from 7.65 Argentine case

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  • Last Post 08 August 2025
Backofthehill posted this 26 June 2025

Was pulling bullets from some 1944 era cases and that's what came out.  In another forum someone suggested that it was Hotchkiss plate glass powder.  Read something about it many years ago but can't recall what.  Anyone seen or heard about it?  Precious little to be found searching the web.

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delmarskid posted this 26 June 2025

Years ago I pulled some WW II 8mm from Romania I think. It was loaded with a shiny black powder that was thin, square and about a tenth of an inch on each side.

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Larry Gibson posted this 26 June 2025

A very common type of powder used by most all European cartridge manufacturers of military rifle cartridges.  It is a Nobel powder or of similar manufacture.  I have found it in most all European milsurp cartridges loaded up through the '50s and '60s.  Was just shooting some FN made Ecuadoran 8x57 with a headstamp of '54 that has the same type of powder.  I have also pulled down a bit of 7.65 Argentine milsurp [FMMAP and SF arsenal] along with some milsurp 7.65 Belgian [FN manufacture] which had the same square cut flake powder. 

I've found all of the same type of powder from numerous milsurp cartridges has the burn rates in the 3031 to 4895 range.   

LMG

Concealment is not cover.........

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Ed Harris posted this 26 June 2025

My experience parallels Larry's. When I was at Ruger working on the Mini Thirty project we did not have a source for 7.62x39 proof loads. I inquired to my European sources and was instructed to simply pull the 123-grain FMJ bullets and to substitute a 7.62x54R 144-grain "L" Ball bullet over the original powder charge. Firing pressure tests in radial copper crusher method the resulting 50,000 cup was lower than the proof we were using in 5.56mm so I worked on another "recipe". The square flake Nobel powder tracked very closely to IMR3031, but to get the desired 60,000 cup proof we substituted the Hornady .312" diameter, 174-grain softpoint .303 British bullet.

73 de KE4SKY In Home Mix We Trust From the Home of Ed's Red in "Almost Heaven" West Virginia

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Backofthehill posted this 28 June 2025

Question for you Ed and anyone else who know. Are the IMR series of powders deterrent coated or do they get their speed simply by their physical shape/pores? 
My experience parallels Larry's. When I was at Ruger working on the Mini Thirty project we did not have a source for 7.62x39 proof loads. I inquired to my European sources and was instructed to simply pull the 123-grain FMJ bullets and to substitute a 7.62x54R 144-grain "L" Ball bullet over the original powder charge. Firing pressure tests in radial copper crusher method the resulting 50,000 cup was lower than the proof we were using in 5.56mm so I worked on another "recipe". The square flake Nobel powder tracked very closely to IMR3031, but to get the desired 60,000 cup proof we substituted the Hornady .312" diameter, 174-grain softpoint .303 British bullet.

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trapdoor4570 posted this 28 June 2025

BACKOFTHE HILL

From all that I have read all IMR, Improved Military Rifle, powders have a deterrent coating.  Introduced around WW1.  SR4759 was not coated so was called Sporting Rifle and just had a graphite coated.  The pre WW1 Pyro DG powder that ate barrels up had a Double Graphite coating.  I salvaged 500 to 700 rounds of ’06 in the mid ‘60s.  thay had a flat base 170 grain bullet cupro nickel jacket and IMR 17&1/2 powder, the ½ indicated it had Tin added to the powder to fight fouling.  I think it was a little slower than IMR3031.  Cases were dated ‘20 and the load card in each bandolier showed 1920 as the assembly date.  Out of all those cases only ONE did not have a full crack from mouth to bottom of shoulder.  They didn’t anneal the cases at Frankford arsenal back then, and they were only 45-47 years old when I broke them down.  Had to throw away several pounds of the powder around 2000.  So the powder lasted around 80+ years.

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Istoic posted this 27 July 2025

I de-milled enough Turkish WWII 8mm to salvage the bullets and powder.  Cases were brittle and primers with click-bangs.  I probably got close to 2 pounds of the square flake powder.  If I remember correctly these Turk 8mm cases under the 154-grain bullet had about 48 grains of this flake powder.  Everyone knows the Turk 8mm is loaded hot.  I will reload using the bullets, new 8mm brass and the square flake powder and reduce down to about 42 - 44 grains eventually.  So, the burn rate is probably in the 3031 to 4895 range according to my studies at the Peruvian Institute of Scatalogical Sciences.

 

Bob

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Larry Gibson posted this 27 July 2025

I have pressure tested numerous lots of the 8x57 Turk milsurp ammunition.  The powder charges have run from 46.1 gr to 48 gr of the flake square cut powder in them.  That powder has been proved to be between 3031 and 4895 in burn rate.  The pull down Turk powder does make an excellent powder to reload the 154 gr FMJs or with a reduced load with cast bullets.  

The Turk 8x57 milsurp was not loaded "hot".  It was loaded to German 8x57 standards.  Out of K98 length barrels or Yugo M48s all of the milsurp Turk I have tested has run 2730 - 280 fps.  The measured psi's run from 53,700 psi to 59,100 psi.  The Tyrk brass appears to not have been annealed properly during manufacture and as stated, it is somewhat brittle.  That can and most often does lead to sticky extraction.  That gives cause for the myth it is "loaded hot".  When the same milsurp load is reloaded in modern cases such a Winchester brass the velocity and psi run the same as the actual milsurp cartridges.  However, extraction is as it should be.  

I've not had any misfire problems with any of the Turk milsurp I've used.  I still have a sealed wooden case of it and probably another 3/4 of a case left. Testing a lot of 1943 Turk 8x57 with 48 gr of the milsurp powder produce a velocity of 2873 fps at 58,700 psi with sticky extraction and some neck splitting on firing.  Pulling some cartridges down and reloading them in the original milsurp cases with the powder charge reduced to 45 gr [6+%] gave 2715 fps at 49,000 psi.  Extraction was normal with no split necks.  That is a very comfortable load.  

A friend of mine pulled down 500 of the Turk milsurp.  He didn't want to shoot the corrosive primers, so he gave the cases to me.  I neck sized and M died all of them and had about 75 split the necks so those were discarded.  The rest of the 400+ cases I loaded with 32 gr of the pull down powder + a dacron filler seating a Lee GB 190 gr GC cast bullet in them.  Runs right at 1850 fpsand is quite accurate and a very pleasant load to shoot.  

LMG 

Concealment is not cover.........

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Istoic posted this 28 July 2025

Guilty as charged repeating the Turk Ammo was hot.  Bad habit repeating things read on the internet without verifying. Seems some folks talked of getting over 3000fps out of some of it back in the day. Probably was the cracked necks and sticky extraction.  It too tried to reduce the load down to 45 grains and used some WW 748 along with the original bullet, but the misfires were so bad I just saved the powder and bullets.

 

Bob

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Larry Gibson posted this 28 July 2025

A friend of mine had a Gewehr 98 with its 29" [+/- whatever] barrel.  We ran 5 rounds of the same Turk lot mentioned above and it was right at 3000 fps.  Barrel length does make a difference.  

LMG

Concealment is not cover.........

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Fiddler posted this 29 July 2025

I'm glad to see that others use pull down powder. There seems to be some folks that get a bit hysterical at the thought of it.

I bought ~700 7mm Mauser a while back, Brazil 1945 - 8. Powder looked like 4064 and a check of the loading manuals showed that charge weight/bullet weight was appropriate for the 4064.  Burned it all up 28-30 grs at a time.

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beemer posted this 29 July 2025

I broke down about 275 rounds of very nice 1986 7.62 X 54. Looked at the books comparing charge and bullet weight, should be very close to 4895. I have about 1 3/4 pounds of nice clean extruded powder and bullets I can use in my 303 Brit.

I tried to sell it but no one was interested, At the price of extruded powder I am way ahead anyway. Going to use it up shooting cast.

My Dad left 8-9 boxes of Mexican made 12 ga magnum shells under his bed. All the bases were corroded but the components were fine. The powder charge worked out as Unique, even looked like it and shot like it.

I don't have a problem using powder from break downs, just use some common sense and do the math. I have also thrown some away, be safe.

 

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Larry Gibson posted this 08 August 2025

If the cases Have an Argentine headstamp then the cartridges were most likely produced at the "Puerto Borghi" Arsenal under Argentine's secrete law No 12,709.  The powder used should be N.N.P. No 1524 made by Koln-Rottweiler.  If the cartridges were "Ss" type with 184 gr +/- FMJBT bullets the charge should have been a nominal +/- 48 gr.  Muzzle velocity was a nominal 2430 fps.

LMG

Concealment is not cover.........

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