Steel case vs Aluminum case

[45_auto]

The steel in every gun barrel I've ever machined was softer than 7.62 x 39 steel cases.

Must have missed that. Someone on here thinks that cheap 7.62 x 39 steel case stuff is harder than something like 4140 (common barrel alloy)?

 

[fallout mike]

And how would steel cases, like this guy told me, possibly damage and wear a barrel out? I asked him if he had some proof of that. Yep, he said the internet.

 

[The Man With No Name]

Must have missed that. Someone on here thinks that cheap 7.62 x 39 steel case stuff is harder than something like 4140 (common barrel alloy)?

No offense meant but how many barrels or slides have you ever machined? 4140 is a relatively stringy but soft steel.

 

[45_auto]

Not many slides, but a LOT of barrels and a lot of 4140 aircraft/rocket parts. I'd expect the steel case stuff to be on the order of A36 properties, which are about half of 4140, but MUCH easier to form and MUCH cheaper.

A36 will be in the low 20's on the Rockwell C scale (hardness), while 4140 is typically over twice that. A36 yield is 36 KSI (duh) vs 80 KSI for 4140, and A36 ultimate is 60 KSI vs 100 KSI for 4140.

This website has a good layman's description of the differences between A36 and 4140:

http://www.precisiongrinding.com/Plate/Steel_Plate/custom_steel_plates.htm

4140 steel plate is an alloy, much harder than the lower carbon steel A36 plate.

 

[Hacker15E]

Rockwell tests of brass, nickel, and steel cases:

http://www.youtube.com/watch?v=qBAh_8usXBI

Nothing like a little actual 'evidence' in the discussion.

 

[The Man With No Name]

Not many slides, but a LOT of barrels and a lot of 4140 aircraft/rocket parts. I'd expect the steel case stuff to be on the order of A36 properties, which are about half of 4140, but MUCH easier to form and MUCH cheaper.

A36 will be in the low 20's on the Rockwell C scale (hardness), while 4140 is typically over twice that. A36 yield is 36 KSI (duh) vs 80 KSI for 4140, and A36 ultimate is 60 KSI vs 100 KSI for 4140.

This website has a good layman's description of the differences between A36 and 4140:

http://www.precisiongrinding.com/Plate/Steel_Plate/custom_steel_plates.htm

I've never understood the point of even testing steel that low in hardness. 20 vs. 40 both machine so easily what is the point? Steel cases used in 7.62x39 are harder. I don't know about other steel cases as I haven't handled them. 4140 is low grade steel (to a toolmaker).

 

[45_auto]

Steel cases used in 7.62x39 are harder.

LMAO - if you say so, then it must be!

Rockwell tests of brass, nickel, and steel cases:

http://www.youtube.com/watch?v=qBAh_8usXBI

Nothing like a little actual 'evidence' in the discussion.

Good video. He got low 70's for aluminum, and low to mid 80's for plain brass, nickeled brass, and steel on the Rockwell B scale. Testing on the coated side (outside) of the steel he couldn't even get a reading because of the softer coating. 81 on the B scale is 0 on the C scale (that's why he used B, they would be too low to even show up on the C). 4140 runs about 50 on the C scale, which is about 115 on the B scale he used in the video. A36 is about 20 on the C scale, which is about 100 on the B scale. So they're using something even softer than A36.

Imagine that, the engineers designing guns and ammo made the barrels harder than the cartridge case, and all the cases are real close to equally soft. Brilliant!!!

 

[wally]

Besides Brass, which is better Steel or Aluminum?

Shooting wise no difference in my experience, although more calibers are available in steel cased. But IMHO the steel cased is better because:

1) you can pick up the empties with a magnet

2) if you don't they will have rusted back to iron oxide dirt in a few years if you don't -- even faster if the are "paving" the firing line with lots of folks walking on them.


Brass and aluminum generally stay there until someone gets around to picking them up, brass never lasts on the ground at our club because even if its not re-loadable its recycle value gets it picked up -- even .22lr.

I've been told the alloy in the aluminum case is not desirable for recycling.

 

[The Man With No Name]

Rockwell tests of brass, nickel, and steel cases:

http://www.youtube.com/watch?v=qBAh_8usXBI

Nothing like a little actual 'evidence' in the discussion.

Finally got a chance to watch that video. Flawed methodology. Not even close. Has anyone here ever actually worked as a toolmaker and actually understands how to properly hardness test things? Easy test. Take some 4140 and take a steel case from a 7.62x39 round and run a file across both. Which one files easier? I feel like I'm trying to explain why you get warm standing in the sun at this point.

 

[45_auto]

Wow. Great explanation of what was flawed about it!

I feel like I'm trying to explain addition and subtraction to someone who can't count.

Here's a link to an explanation and the history of Rockwell testing for you:

http://en.wikipedia.org/wiki/Rockwell_scale

Here's the international engineering hardness standard for metallic materials (ISO - International Organization for Standardization):

http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=37743

And here's the American one (ASTM - American Society for Testing and Materials):

http://www.astm.org/Standards/E18.htm

You don't even have to buy the standards, just look closely for the words "file" or "rockwell" in the titles.

Here's you a quick guide to buying tool steel online. Scroll down to the specs for the different grades and notice how they specify the hardness:

http://www.onlinemetals.com/toolsteelguide.cfm

 

[Hacker15E]

Finally got a chance to watch that video. Flawed methodology. Not even close. Has anyone here ever actually worked as a toolmaker and actually understands how to properly hardness test things? Easy test. Take some 4140 and take a steel case from a 7.62x39 round and run a file across both. Which one files easier?

Sooooooooo, you're saying that someone using a tool designed to actually measure hardness has 'flawed methodology', but that the way to prove that is dragging a file across two items, and subjectively determining which "files easier"?

Interesting concept of the scientific method.

 

[The Man With No Name]

More accurate than taking work hardened materials, not using the correct diameter balls for the materials tested, testing on the incorrect scale (which makes the test inaccurate for the materials), using material that are not flat and which any spring back ruins the test, ect. I don't need to read those links. I'm not someone that isn't familiar with the methods. I'm saying you might as well go old school and get a set of rated files if you want to take that video as gospel. My knowledge is at the advanced end of the scale. Look up Charmilles. In the 80's I assisted them in developing generators to cut materials they had never cut before in their wire EDM machines. Look up Autodesk. I was one of the first in this country that actually made their software work in that I was able to generate programming directly off of solid models. This stuff just seems so basic and the test so flawed that I am having a hard time believing that anyone even believes it.

 

[Hacker15E]

Well, if that's the case, then how about you point us all in the direction of some other specific evidence -- anything -- that shows that steel cartridge cases are "harder" than a firearm chamber?

If it's "so basic", then there must be something that is easily producible, right?

 

[45_auto]

not using the correct diameter balls for the materials tested

No wonder you're so confused. You really need to learn how hardness testing works. Rockwell testing uses a specific size ball and a specific load for each scale. The material is irrelevent. Scary to think that you've been misunderstanding basic stuff like that for 30 years.

A HRA 60 kgf 120° diamond cone† Tungsten carbide
B HRB 100 kgf 1⁄16-inch-diameter (1.588 mm) steel sphere
C HRC 150 kgf 120° diamond cone
D HRD 100 kgf 120° diamond cone
E HRE 100 kgf 1⁄8-inch-diameter (3.175 mm) steel sphere
F HRF 60 kgf 1⁄16-inch-diameter (1.588 mm) steel sphere
G HRG 150 kgf 1⁄16-inch-diameter (1.588 mm) steel sphere

Look up Autodesk. I was one of the first in this country that actually made their software work in that I was able to generate programming directly off of solid models.

Look up Pro/E and Solidworks. I did the same thing for them about 10 years before you did it with Autocad (1988 for Pro/E, 1996 for Solidworks). I believe Autocad went 3D with Inventor around 2000. We were working on it with Uni-graphics in the early 80's at McDonell-Douglas For the C-17 but I left there in 1985.

 

[The Man With No Name]

No wonder you're so confused. You really need to learn how hardness testing works. Rockwell testing uses a specific size ball and a specific load for each scale. The material is irrelevent. Scary to think that you've been misunderstanding basic stuff like that for 30 years.

A HRA 60 kgf 120° diamond cone† Tungsten carbide
B HRB 100 kgf 1⁄16-inch-diameter (1.588 mm) steel sphere
C HRC 150 kgf 120° diamond cone
D HRD 100 kgf 120° diamond cone
E HRE 100 kgf 1⁄8-inch-diameter (3.175 mm) steel sphere
F HRF 60 kgf 1⁄16-inch-diameter (1.588 mm) steel sphere
G HRG 150 kgf 1⁄16-inch-diameter (1.588 mm) steel sphere



Look up Pro/E and Solidworks. I did the same thing for them about 10 years before you did it with Autocad (1988 for Pro/E, 1996 for Solidworks). I believe Autocad went 3D with Inventor around 2000. We were working on it with Uni-graphics in the early 80's at McDonell-Douglas For the C-17 but I left there in 1985.

1. And testing certain materials on cetrain scales in not accurate. Very basic.
2. Pro/E and Solidworks I liked but honestly thought was a more basic software and not suited to what we were doing. Also I found that instant response to software issues was not there back then. Plus I found it just plain didn't work and wasn't hackable as other companies software which was what I wanted since everyone said they had software that would work but no one actually did. I can't tell you how much of my life I wasted on phone until I figured out it wouldn't work unless I made it work.

 

[splithoof]

You guys sound like a bunch of typical mechanical engineers who have been locked up in a lab for too long.
Here it is for me: Buy gun; Shoot gun with whatever works to my satisfaction; Clean gun every once in a while; Put gun away when done (or carry); Go home to play with cat. Bottom line: who cares???

 

[gbeecher]

Academic debate but a non-issue...

Why do people always debate this topic? I have a Mosin-Nagant 1891/30 and shoot both lacquer coated and zinc plated steel cased ammo. I have never had any problem in 2+ years of shooting and some 210 rounds downrange. I'm assuming the receiver, chamber and barrel steel are harder or at least as equally hard as the cartridge case. Why would anyone design a firearm where the cartridge case marred or scraped the steel of the receiver, chamber or bore? As long as you shoot the proper ammo that your gun was originally designed for - you're good to go!

 

[Tcruse]

The case is only one part of the equation. Normally, US ammo is a bit more expensive and has all of the components a bit higher in quality. Steel cased ammo is generally for eastern block manufacturers that operate at a lower price point, so cheaper case, cheaper power, cheaper jacket material. There are some exceptions, I have seen some really good steel case ammo from time to time, but it never seems to be available over a long time frame.

The CCI aluminum cased ammo is first class and is an attempt to provide a non-reloadable case at a better price. In this area the aluminum cased ammo is higher that Winchester and federal range ammo. The nylon jacketed ammo is also noted for being more clean than alternatives.