Steel cartridge case manufacture


#1

In idle moments I like to trawl through Google patents as there are always interesting things to find.

The latest is this patent for the manufacture of steel cartridge cases. Dated 1949 it’s a late entrant to the field and I can’t help but feel that most of the work was done by the Germans a good thirty years earlier.

google.com/patents?id=K41tAA … on&f=false

Can anyone find anything unique about this patent? Something that hadn’t been done before?

Happy collecting, Peter


#2

Peter, The fact that it was filed in Philadelphia in May 1945 tells me that this patent was by guys who worked on the development of steel cartridge cases at Frankford Arsenal during WWII. The first paragraph is a dead giveaway because it grants the military free use of the patent which indicates the guys did this work as part of their government work and on government time. The patent just gives them some control if steel cases caught on in the commercial ammunition world in the US.

Interesting document—thanks!

Lew


#3

Frankford Arsenal was making steel cased ammunition in 1908

(I have a .30-06 draw headstamped " F A 9 08 " & my next date in steel is " F A 19" ).


#4

What I find strange is that the purpose of a patent is to give a period of exclusive use in return for making an invention public by disclosure. It is the word ‘invention’ that is important here in that the disclosure must be of something new. By 1945 there was little that was new in the production of steel cased ammunition.

You can’t claim patent rights over something already in the public domain unless you are claiming substantial improvements to the item concerned. If I could I’d be at the Patent Office tomorrow filing a claim on the wheel and the transistor. Sadly, that route to wealth is ruled out because, as the New Yorker cartoon said … “It’s been done”.

Happy collecting, Peter


#5

I did not read the patent, but it is possible that the claims made covered some new or improved method of manufacture, as distinguished from the end product. That would have also been patentable as an invention, and indeed many patents address method of manufacture.

During WWII, billions of steel-cased .45 ACP and .30 Carbine cases were made at Evansville, therefore the manufacturing technology must have been well established well prior to the war. There was considerable R&D performed on the manufacture of steel (and other metal) cartridge cases in various locations in many countries during and after the war.


#6

The unique feature of this patent is stated, starting at the bottom of of column seven. It consists of a novel heat treatment of the plain, low carbon steels in order to provide improved case properties. This patent is highly detailed. Most of the information covers the normal annealing and cold working of the case material, and all of the almost trivial details of lubrication and cleaning. The patentees add a temper and heat treat that apparently is not normally used, probably because the 1015 and 1030 steels are not considered to be heat treatable due to their low carbon contents(0.15% and 0.30% respectively). The carbon level for heat hardening steels is considered to start at about 0.50 %.

Something that is not clearly stated in this patent, is the type of steel normally used in steel cartridge case fabrication. In outside research earlier this winter, I found the recommended steel to be “Special Drawing Grade 1008 Steel” (0.08% carbon). I will try to cite my source on this later, as it will take some time to check my books. This steel is a “thoroughly killed and rimmed steel” which means special steps are taken to minimize the absorbtion of gases into the steel as the ingot is smelted and poured at the foundry, then removal of any flawed portion of the ingot before it is forged into a billet prior to cold rolling. The most troublesome flaws are piping, which are voids that occur as gases escape from the metal upon cooling, and shrink voids, formed by contraction upon cooling. These flaws are mostly confined to the upper end of the vertically cast ingot. This bad end is cut off, leading to a higher waste factor. All of this means that an expensive grade of low carbon steel is the norm for cartridge cases. It would appear, although it is not clearly stated in this patent, that the authors are also using a lower than typical cost material in the form of regular cold rolled 1015 and 1030 steel. I don’t know if “Special Drawing” grades of these steels are available.

I don’t know what the normal failure rates for brass or steel cartridges are, but the number of ruptures listed in the testing section seems rather high, even though they appear to be bragged about. Maybe steel cases are actually more problematic in use than I have been lead to believe.

Thank You Enfield56 for bringing this patent to my attention. It provides me with a wealth of details that I have been interested in. Curt Laws


#7

ASTM Specification A1008 contains information regarding several types of cold-rolled drawing steels used for different degrees of drawing, including, shallow, deep, and extra-deep drawing steels, (EDDS, degassed and chemically stabilized). I do not have a copy of this spec, as ASTM charges for it, so I do not know any more than that.

I suspect that direct inquiry to any university having a degree program in metallurgy or metallurgical engineering could lead you to a lot of valuable material you probably couldn’t find on the internet.


#8

It is usually a shortage of material that brings on such. During WWII Vice President Henry Wallace took interest in such and spurred on revised research by our ordinance works. In HWS Vol. II it is noted that there was an official designation given for steel cased cartridge, Ball, Cal. .30 of T22. It also states that production totals from October 1942 thru June of 1944 at Frankford and other Ordinance plants produced some 17,200,000 casings for loading. This is why we still see so much this M2 Alternate Ball, M1909 Blank and M2 AP around today here in the US…

Joe


#9

There is a Frankford Arsenal report on lubrication in the drawing of steel cases that can be downloaded from www.dtic.mil using report number ADA953424