why would the russia use steel cases vs we use brass cases is there any difference is there any advantage, seems like steel would be better in case of dangerous pressure rise due to blockage.

cost reduction. Brass will normally seal better. Steel usually dirtier. Found this interesting.
http://www.luckygunner.com/lab...vs-steel-cased-ammo/

Has anyone been reloading any steel cases ? roger

Interesting article. We see a cost advantage. The Russians had a lot of steel but not much copper. Copper was saved for wire and mild steel was used for ammunition.

quote:

Originally posted by bartsche:
Has anyone been reloading any steel cases ? roger

i had in the past

Yep, steel cases way cheaper, but only good for original loading. Steel cases aren't as malleable as brass cases and don't "spring back" after firing. The coating on steel (corrosion preventative) is often a problem too during sizing. I've tried reloading 45 ACP steel cases outta curiosity, and got 2 and sometimes 3 reloadings before splits begin to happen. I read of a feller that reloaded some .223 steel cases 10 times without too many problems (hard sizing, much lower case life, etc.) but that was the only time I've read of anyone trying that many loads...

Don't forget; the US used some steel cases in WW2 as well, and we even made steel pennies.
The Germans used a lot of steel cases in WW2.
Copper (and tin) is always a scarce, strategic material and we should conserve it when possible.

quote:

Copper (and tin) is always a scarce, strategic material and we should conserve it when possible.

The anti mining crowd have been doing the conserving for us killing several very high grade copper mines

https://groups.google.com/foru...lM1NJe0/cBSU4bR2jz8J

quote:

John Bercovitz (JHBercovitz@lbl.gov)

I see that that article was sort of long. Let me preface it by giving you a bare bones synopsis. A brass cartridge case expands past its yield point during firing, at least for the first firing when the case doesn't fit the chamber so well. That is to say, it stretches plastically to some new size and then springs back from that new size to its new relaxed size.

If that springback is greater than the springback of the steel chamber, then the case will extract easily. If not, the case will want to be larger than the sprung back chamber and so it will be a "press fit" in the chamber and will be difficult to extract. This extraction difficulty appears approximately when chamber pressures exceed 70,000 psi.

jb

Here's the article:

A friend asked why steel cases aren't more common since they would allow higher chamber pressures. I thought that as long as I had written something up for him, I might as well post it here:

Material Properties

CDA 260 cartridge brass: barrel steels:
Young's modulus = 16*10^6 psi Young's modulus = 29*10^6 psi
Yield stress = 63,000 psi min. Yield stress: usually > 100,000 psi

I was going to get back to you and explain further why brass is a better cartridge case material than steel or aluminum. Sorry I took so long. I left you with the nebulous comment that brass was "stretchier" and would spring back more so it was easier to extract from the chamber after firing. Now I'll attempt to show why this is true given the basic material properties listed above.

A synopsis would be that the propellant pressure expands the diameter of the thin wall of the cartridge case until it contacts the interior wall of the chamber and thereafter it expands the case and the chamber together. The expansion of the cartridge case, however, is not elastic.

The case is enough smaller in diameter than the chamber that it has to _yield_ to expand to chamber diameter. After the pressure is relieved by the departure of the bullet, both the chamber and the cartridge case contract elastically. It is highly desirable that the cartridge case contract more than the chamber so that the case may be extracted with a minimum of effort.

A quick review of the Young's modulus: this is sort of the "spring constant" of a material; it is the inverse of how much a unit chunk of material stretches under a unit load. Its units are stress / strain = psi/(inch/inch).

Here's a basic example of its use: If you have a 2 inch by 2 inch square bar of steel which is 10 inches long and you put a 10,000 pound load on it, how much does it stretch?

First of all, the stress on the steel is 10,000/(2*2) = 2500 psi.
The strain per inch will be 2500 psi/29*10^6 = 0.000086 inches/inch.

So the stretch of a 10 inch long bar under this load will be 10 * 0.000086 = 0.00086 inches or a little less than 1/1000 inch.

Yield stress (aka yield strength) is the load per unit area at which a material starts to yield or take a permanent set (git bint). It's not an exact number because materials often start to yield slightly and then go gradually into full-scale yield. But the transition is fast enough to give us a useful number.

So how far can you stretch CDA 260 cartridge brass before it takes a
permanent set? That would be yield stress divided by Young's modulus:

63,000 psi/16*10^6 psi/(inch/inch) = .004 inches/inch.

How far can you stretch cheap steel? Try A36 structural steel:

36,000 psi/29*10^6 psi/(inch/inch) = .001 inches/inch.

How about good steel of modest cost such as C1118?

77,000 psi/29*10^6 psi/(inch/inch) = .003 inches/inch.

(Note that C1118 doesn't have anywhere near the formability of CDA 260. Brass cases are made by the cheap forming process called "drawing" while C1118 is a machinable steel, suitable for the more expensive machining processes such as turning and milling.)

What about something that's expensive such as CDA 172 beryllium copper?

175,000 psi/19*10^6 psi/(inch/inch) = .009 inches/inch.

(This isn't serious because CDA 172 is pretty brittle when it's _this_ hard. Not to mention that beryllium is poisonous even in an alloyed state.)

Note: I was corrected on this. It seems that very low alloys of beryllium are _not_ considered poisonous (except here at this Lab. 8-))

Titanium Ti-6AL-4V

150,000 psi/16.5*10^6 psi/(inch/inch) = .009 inches/inch

(This is an excellent material though expensive and hard to work with.)

Really expensive aluminum, 7075-T6

73,000 psi/10.4*10^6 psi/(inch/inch) = .007 inches/inch

Cheap aluminum, 3003 H18

29,000 psi/10*10^6 psi/(inch/inch) = .003 inches/inch

(Aluminum isn't a really good material because it isn't strong and cheap at the same time, it hasn't much fatigue strength, and it won't go over its yield stress very often without breaking. So you can't reload it. It makes a "one-shot" case at best. Also, 7075 is a machinable rather than a formable aluminum, primarily.)

Magnesium, AZ80A-T5

50,000/6.5*10^6 = .0077

(Impact strength and ductility are low. Corrodes easily.)

+Here's the important part: Even if you stretch something until it +yields, it still springs back some distance. In fact, the springback +amount is the same as if you had just barely taken the thing up to its +yield stress. This is because when you stretch it, you establish a new length for it, and since you are holding it at the yield stress (at least until you release the load) it will spring back the distance associated with that yield stress. So the figures given above such as .004 inches/inch are the figures that tell us how much a case springs back after firing.

Changing subjects for a moment: How much does the steel chamber expandand contract during a firing? Naturally this amount is partially determined by the chamber wall's thickness. The outside diameter of a rifle chamber is about 2 1/2 times the maximum inside diameter, typically. The inside diameter is around .48 inches at its largest. Actual chamber pressures of high pressure rounds will run 60,000 psi or even 70,000 psi range if you're not careful.

One of the best reference books on the subject is "Formulas for Stress and Strain" by Roark and Young, published by MacGraw-Hill. Everyone just calls it "Roark's". In the 5th edition, example numbers 1a & 1b, page 504, I find the following:

For an uncapped vessel:

Delta b = (q*b/E)*{[(a^2+b^2)/(a^2-b^2)] + Nu}

For a capped vessel:

Delta b = (q*b/E)*{[a^2(1+Nu)+b^2(1-2Nu)]/(a^2-b^2)}

Where:
a = the external radius of the vessel = 0.6 inch
b = the internal radius of the vessel = .24 inch
q = internal pressure of fluid in vessel = 70,000 psi
E = Young's modulus = 29 * 10^6 psi for barrel steel
Nu = Poisson's ratio = 0.3 for steel (and most other materials)

A rifle's chamber is capped at one end and open at the other but really it's not too open at the other end because the case is usually bottle- necked. You'd have to go back to basics instead of using cookbook formulae if you wanted the exact picture, but if we compute the results of both formulas, the truth must lie between them but closer to the capped vessel.

For an uncapped vessel:

D b = (70000*.24/29*10^6)*{[(.6^2+.24^2)/(.6^2-.24^2)] + .3} = .00097

For a capped vessel:

D b = (70000*.24/29*10^6)*{[.6^2(1.3)+.24^2(.4)]/(.6^2-.24^2)} = .00094

There's not a whole heck of a lot of difference between the two results so let's just say that the chamber's expansion is .001 inch radial or .002 inch diametral.

The cartridge case's outside diameter is equal to about .48 inch after the cartridge has been fired. So its springback, if made from CDA 260, is

.004 inches/inch (from above) * .48 inch = .002 inches diametral

which of course is just the amount the chamber contracted so we've just barely got an extractable case when chamber pressures hit 70,000 psi in this barrel. This is why the ease with which a case can be extracted from a chamber is such a good clue as to when you are reaching maximum allowable pressures. By the same token, you can see that if a chamber's walls are particularly thin, it will be hard to extract cases (regardless of whether or not these thin chamber walls are within their stress limits).

A really good illustration of this can be found when comparing the S&W model 19 to the S&W model 27. Both guns are 357 magnum caliber and both can take full-pressure loads without bursting. The model 27 has thick chamber walls and the model 19 has thin chamber walls. Cartridge cases which contained full-pressure loads are easily extracted from a model 27 but they have to be pounded out of a model 19. So manufacturers don't manufacture full-pressure loads for the 357 magnums anymore. 8-(

We can see from the above calculations that a steel case wouldn't be a good idea for a gun operating at 70,000 psi with the given 2.5:1 OD/ID chamber wall ratio if reasonable extraction force is a criterion. Lower pressures and/or thicker chamber walls could allow the use of steel cases.

jb

As noted by another author, steel does not retract as well as brass, but it is far cheaper. Drag reduction between steel case and steel chamber was investigated heavily in the 1950's for small arms and machine canon. I have an American Rifleman article, from the 70's I think, they have a picture of a Teflon coated steel 30-06 case. The basic problem of reducing case to chamber friction was studied, waxed cases were tried, the absolute best was Teflon coated with an oiler mechanism on the gun. As the Teflon coated steel rounds were fed into the chamber, an oiler put a drop of oil on each round. The following are excerpts from the report


A LABORATORY INVESTIGATION OF CARTRIDGE LUBRICANTS FOR 20MM F.A.T.-16 STEEL CARTRIDGES

quote:

After the Frankford Arsenal learned of the NRL work with Teflon coatings for cartridges, an Army Ordnance project was established at the Proctor Electric Company to put Teflon coatings on the steel F.A.T.-16 cartridges manufactured there. However, certain difficulties arose in obtaining good corrosion resistance with Teflon, apparently due to the manufacturing methods used.

Since the use of light oil coatings over Teflon-coated guns has a beneficial effect on rate of fire, it was necessary to repeat the firing tests previously performed on all test ammunition. This resulted in a significant increase in the rates of fire. Thus, oiled brass cartridges averaged 789 rpm, oiled bare steel cartridges averaged 789 rpm, "Case-Cote" wax-lubricated cartridges averaged 820 rpm and Teflon-coated cartridges 810 rpm. However, it should be noted that these high rates of fire are not obtainable on a bare steel gun with oil. It was reported in reference (1) that oil on a Teflon coated gun with properly lubricated ammunition usually produces rates of fire 40-75 rpm higher than normal

Patents were issued for Teflon coatings, reading the text is interesting, though far too long to insert in a thread.

http://www.google.com/patents/US4041868

quote:

Polytetrafluoroethylene
US 4041868 A 1977

A thin walled steel cartridge case having a substantially larger internal volume than a conventional cartridge case. The cartridge case is fabricated from a high strength, heat treated carbon steel or boron steel and the wall contour in the head area is designed to avoid localized high stress. A low friction coating is applied to the outer surface of the cartridge case and serves to reduce stress concentrations in the head area and to reduce extraction force in the event of interference between the case and the chamber during extraction

Ammunition cartridge cases US 2972947 A

Teflon Coating Ammunition

http://www.google.com/patents/US2972947

Feb. 28, 1961 V. G. FITZSIMMONS ET AL AMMUNITION CARTRIDGE CASES Filed Sept. 30, 1954 SIN TE R E D POLYTETRAFLUOROETHYLENE 1NVENTOR5 WILLIAM A. ZISMAN VINCENT G. FITZSIMMONS ##w if ATTORNEYS 2372,97 Patented Feb. 28, 1961 (Granted under Title 35, US. Code (1952), sec. 266) 2 Claims.

Ever wonder why our M256 120mm Tank Cannon uses steel cartridge cases? (They are also very short with a rubber obturator).
And they operate at above 100,000 psi?
To save brass. And because they use screwed in, steel primers.
Anyone remember the "Steelhead" cases of the 1970s? It is the primer that is the weak link.
Russia and China use mostly steel small arms cases; plated with brass or copper.

quote:

Originally posted by bartsche:
Has anyone been reloading any steel cases ? roger

Yes, some tula 223 is boxer primed. Reloads just fine. I do get some split necks though.

quote:

Originally posted by dpcd:
Ever wonder why our M256 120mm Tank Cannon uses steel cartridge cases? (They are also very short with a rubber obturator).
And they operate at above 100,000 psi?
To save brass. And because they use screwed in, steel primers.

Only the base is steel. The case is combustible. The peak pressure is 73,900 psi

I was the item manager for tank ammo at AMCCOM, at Rock Island Arsenal, and later was the TACOM team leader for the M256 Cannon. And I was in a few tank units in my Army career, the last one being a Tank Battalion Commander. So I do know a little something about tank ammo and cannons. The early M256E3 ammo, now type classified as A3, generated some pressures around 100K psi and ARDEC was worried about tube fatigue. They standardized the pressure at 81000 psi.

You did not use the new generation designator E3 in the original post

During WW2, I would buy black market 45 auto steel cases by the case, they were for the Thompson sub machine guns.. That and GI ball ammo was the only ammo one could get back then, and it was on the black market...I did attempt reloading a few but it was hard on dies I found out and cases tended to split and it bordered on scary vs. nada ammo! The final result was don't reload them and don't shoot them in your good pistols! A brass case back then would fetch a $1.00 each, that was a lot of money in the days of nickel beer in Juarez.

So Ray? You were buying cases of ammo and drinking beer in Mexico when you were under 10 years of age? WW II ended in 1945 correct?

quote:

Originally posted by Atkinson:
During WW2, I would buy black market 45 auto steel cases by the case, they were for the Thompson sub machine guns.. That and GI ball ammo was the only ammo one could get back then, and it was on the black market...I did attempt reloading a few but it was hard on dies I found out and cases tended to split and it bordered on scary vs. nada ammo! The final result was don't reload them and don't shoot them in your good pistols! A brass case back then would fetch a $1.00 each, that was a lot of money in the days of nickel beer in Juarez.

In case it gets edited!

Give Ray a Break. He would have been at least 14 at the end of WWII. Ray was a Texacan at the time. So: it is Probable that He had to drive his younger brothers to Mexico on Friday nights cause they could not see over the dashboard. Beer cause it was hot with no air conditioner and 45 ammo cause you sometimes had to fight your way back out of Juarez back in the day. Still do I hear...

RCG,
For your information, my dad had the old Threadgill ranch just out of Ft. Bliss,(El Paso) and a contract to let the Army bury the left over stuff at the end of a term?? It consisted of ammo, some guns, gasoline lots of tea and coffee,an all kinds of stuff..Apparantly they did this because if they had anything left over it would mean the budget would be cut to allow for that non use..All this goes back a long ways so Im doing my best!

At any rate dad dug it up and gave away stuff and sold some stuff, I got a 45 and a carbine for my digging efforts and a little ammo and at some point the ammo ran out and had to buy it with money I made digging post holes and herding goats.. I don't remember my age but I was in grade school, probably 8th grade??. I was older than 10 but not much, so what, I had a horse, a 22 rifle, and a 25-35 deer rifle when I was 10 and shot my first deer, as did both of my 8 years old, so you must have lived and awfully protected life up North with all them Yankee carpet baggers!!Besides that ww2 may have been over?? but stuff was still rationed and you had "A" sticker on the pickup to buy gas and tea and coffee brought dad a premium, I went several years without ammo for the 25-35 and hunted deer with the carbine, a pathetic excuse for a deer rifle, finally used nothing but head shots.... who gives a hoot, its been a year or two..

My big brother drove ME to Juarez, for nickel beer and like any good Texas boy to the red light district to introduce me to ladies of the evening! and that was so scary that I missed that opertunity and got a lot of ribbing over it!!

So there ya go!

Ray,

Look at what you originally wrote and your subsequent comments to my post. What year were you born? 1935? If accurate, that makes you 10 at the end of WWII.

I'm not the one making these claims. You are. Your words. oh well...

Could be, WW2 and the war with Japan was at the same time, I was older than 10 probably, but that's been what 70 years ago, at any rate a long time ago..If that worries you then you need a full time job..your making much out of nothing..

Next problem reloading russian/chinese steel is that most of it is Berdan primed.

Yes thats right that shitty brass/steel is the brainchild of a fellow American, you must be so proud?