03a3 Max pressure

[EO1]

Does anyone know the official spec for maximum working pressure of a Rem (or SC) made 1903/1903a3 ?

[PhillipM]

50,000 psi working. Proof load was 70,000... That may have been raised to 75,000.

[EO1]

Do you have a reference source for that ?

[PhillipM]

Hatcher's Norebook. Standard M2 ball spec is 50,000 regardless of rifle or machinegun. The 03A3 was built to fire that ammunition. The 70,000 psi load is called a blue pill. For the rifles to be accepted, this round had to be fired, earning the rifle it's P proof mark.

[EO1]

Thankee.

[raymeketa]

The specified pressure of both the standard service ammunition and the high pressure test cartridges can be found in any number of places such as TMs and FMs. SAAMI also has their own Service Max and Proof Cartridge Max specs. The numbers can vary but 50,000 and 75,000 psi are considered nominal.

Max pressures for the 03A3 rifles themselves is another thing altogether. You'd have to find official documents that give this information. Contemporary reports seem to indicate that 75000 psi was at or near the upper limit. OTOH, tests of the Garand documented pressures well over 100,000 before things began to go bad. Testing rifles to destruction is not something that manufacturers like to do because what destroys the rifle will also destroy the test equipment.

[Parashooter]

In modern terms, that's 50000 C.U.P. (Copper Units of Pressure) maximum average pressure (MAP), as determined in by the old standby copper crusher type gauge. This method has now been largely superseded by the piezo transducer system, which can give a more precise reading of peak pressure. With the transducer method, MAP for the .30/06 cartridge is 60000 psi - same actual pressure but different units. Many old references gave crusher figures as "psi" but that usage has been outdated for many years. The two systems and units have become a source of much confusion to those with limited exposure to internal ballistics. This text and table from a 1987 Hercules data guide may help clarify the difference -

http://i52.tinypic.com/6gzh47.jpg

[chuckindenver]

proof test,,,125,000 blue pill

[raymeketa]

Is that a test for the barrel only?

[chuckindenver]

receiver, and barrel together... keep in mind thats max pressure,, not what the proofed all rifles at.
like the other posts.. 50 to 75,000 was average pressure

[raymeketa]

Now I'm confused. The so-called "blue pill" was loaded to 75,000 psi max. It was called a blue pill because it was loaded with a lead bullet and the case was stannic stained for identification. The stannic stain gave the case a bluish appearance.

Barrel proof cartridges were often manufactured without a rim because they were used only to test barrels at an early stage of construction. But even they were usually loaded to less than 100,000 psi.

So what was that 125,000 psi cartridge used for?

[chuckindenver]

spend some time with Hatchers note book..

[PhillipM]

"Before any barrel is accepted for service it is proof fired with a high pressure test cartridge, or "blue pill," which gives about forty per cent higher pressure than the service load. These test cartridges are tin plated to make them look different from the regular cartridges, and this gives them a bluish white color, hence the name "blue pill."

When I was at Springfield, the regular service load gave a pressure of around 50,000 psi, and the blue pill at first gave 70,000 pounds; which we later raised to 75,000 pounds, as will be explained further along."

Hatcher's Notebook page 198

[raymeketa]

spend some time with Hatchers note book..

With all due respect Chuck, I use Hatcher as one of my primary references, as well as several other sources. I also collect US Military ammunition.

What specific Hatcher note are you citing for the 125,000 cartridge?? Ordnance Office note 471.41/84 dated April 1917 is very similar to the Hatcher note posted by PhilipM, above.

Ray

[chuckindenver]

i may be off on the amount of pressure, havnt opened a book in a few years,. honestly pressure really hasnt been an issue with anything iv done as a smith

[mhb]

proof test,,,125,000 blue pill

is the standard proof load, not an intentional torture test overload, and was so-called because the specially-manufactured brass cases were tin-plated for identification. The original 1906 proof load was 70 kpsi, which was later increased to 75 kpsi in an effort to eliminate any marginal action components, after the initial problems with heattreatment came to light.
Hatcher reported on extreme overloads (up to 133 kpsi, IIRC), which the DHT actions were able to withstand intact, but such loads were never anything but a demonstration of the ultimate strength and much improved margin of safety in the DHT actions.

mhb - Mike

[Cosine26]

The proof pressure was changed from 70K to 75K after WWI to eliminate the Avis Barrel that had problems due to the method of manufacture according to Hatcher.
FWIW