Gun metal-lurgy
We're warned about using modern, smokeless ammo in 19th century small arms: "The steels were inferior."
Can anyone comment, expertly, on how gun steel might have changed in the past 100+ years? Now I'm not asking about Damasced (?) barrels. I asking about the gun metal itself.
bobguz
Can anyone comment, expertly, on how gun steel might have changed in the past 100+ years? Now I'm not asking about Damasced (?) barrels. I asking about the gun metal itself.
bobguz
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The metal has not changed as much as the heat treatment has, and the danger is more in the speed that the powder burns than the steel.
The small changes to the steel alloys added a few elements that increased the strengths of the steel when heat treated and drawn back. Modern heat treating was a new science and they learned how to molecularly align the molecules of the elements (especially carbon) for a higher tensil strength. This allowed the equilivent strength in a thin wall tube of what would have required a much thicker wall in the older guns.
The main worry is the powder. Newer (smokless) powder burns much more effeciently than the old black powder. That creates the pressure much quicker, and at higher levels. In an old black powder gun, if you overloaded the powder, it would just blow out the end of the barrel (unburned) because it burned so slowly that it could not finish the burn before the ball left the end of the barrel. The shorter the barrel, the less powder burn, the less velocity.
Modern powder comes in many versions which have different burning rates. Thats why you can't use pistol powder in rifles. At any rate, they burn so quickly that the pressure reachs pressures much higher than the old powders befor the ball (or projectile) exits the barrel. That's what blows them up!
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the above post is correct in some parts but the major difference id the aditives used to harden steel. steel is just iron with carbon added, alloy steel has additional metals added (mangenese, cromium, nickel, ect.) no rifle barrels are heat treated for strenght, all rifle barrels are dead soft alloy steel. when a rifle barrel is stess relieved it means it is annealed after machining (rifled and turned to finish dimentions). in thirty years as a gunsmith i have only seen one rifle barrel that was heat treated, a jap. browning auto with a hardend feed ramp. 0 -
Hi Mike:
What about receivers? Receivers are hardened, are they not? Have those processes have changed ofer the years? Can you fill us in?
By the way, steels and hardening treatments were not the only factors. Design elements improved also. For example, escaped gas management is vastly better in later Mauser designs than earlier ones.
redcedars
Edited by - redcedars on 08/22/2002 19:42:060 -
This is a big subject and hard to be brief on. An example might be best. A group of surviving 1918 WW1 rotary aircraft engines were examined for use in restored/reproduction antique airplanes. When the forged crankshafts were xrayed they found large slag inclusions within the steel making more than 3/4 of them unsafe for flight.
Older steelmaking processes like the Bessemer Converter produced dirty steel. When cast iron is converted from steel it is poured into long vertical moulds. The slag floats to the top and the top is cut off and discarded. Then the billet is rolled into bars,structural shapes and sheets. Depending on the quality, more or less of the "Hot Top" is cut off,resulting in more or less inclusions being rolled into the steel ending up as invisible seams.
In the mid 1960s I was involved in an investigation of a gear failure in a powered scaffold that caused several deaths. The gear was made from prehardened 4140 steel bar stock. A microscopic examination showed it broke through a slag inclusion. So being a properly heat treated alloy steel is only part of strength criteria. Steel for highly stressed applications has to be clean of inclusions and detrimental chemical elements like phosphorus and sulphur carefully controlled to within specifications.
Aircraft quality, gun barrel quality and other special use steels, in addition to being clean of inclusions and gasses are very closely chemically controlled. They come with certifications and test specimens.
Recently a firearms expert was killed when the bolt blew back out of an 1899 6mm Lee Navy service rifle, going through his skull. I've also heard of a Newton and at least one early British sporter barrel letting go.
Because of advances in steelmaking since WW2, todays' guns are a safer bet for high pressure cartridges.0 -
An error- cast iron is converted to steel not the other way around.
Damascus steel was superior to other late 19th century barrel steel for shotgun barrels because it could be made thinner walled and stronger. The process involved rolling out several thin strips of wrought iron and steel, twisting them together and rerolling into a strip, all at red heat. The final strip was wound on a mandrel and forged, welding it into a tube. All this forging, spread out any local concentration of inclusions and weaknesses and gave a spiral (really helical) grain flow of the steel which is more resistant to pressure in a tube. Assuming all welds were good the result was a superior strength, lightweight shotgun barrel. The alternate strips of wrought iron and steel gave an attractive pattern and sold at a premium over
the plain steel barrels of the time.0 -
v35, i stand by what I said, cast iron is not pure iron (fe) most carbon steels have about 2-3% carbon while 'cast iron' has about 12/14% as well as other things.i could be wrong about the percentages (as well as other things in life). as to receivers; yes most of them are heat treated to harden them in some way. also there have been many mechanical advances in the last century to be sure ie; the above mentioned m-98 mauser ect. 0 -
Mike, I think what v35 is saying is you said:
"When cast iron is converted from steel"
Should have read"
"When cast iron is converted to steel"
"from" should have been "to".
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