Stainless Steel

Petrol & Powder

Well-Known Member
In another thread (copper removal) the topic of stainless steel came up and Snakeoil provided a very good overview of stainless steel.

I have seen stainless steel rust, and more than just a few times. There are a lot of variables including the type of stainless steel (it’s not all the same) and the conditions. While stainless steel is a huge improvement over carbon steel in terms of avoiding rust, it is probably better to think of it as rust resistant rather than rust proof. In addition to the rust resistant properties of stainless steel, it is also very hard. This can be a good thing or a bad thing, depending on the application.

I have repaired a few stainless guns belonging to others that had rusted, including one rifle that had rusted shut.

Today’s gun owners probably don’t think much about stainless steel, but for those of us that have been around a while, stainless steel was a bit of a leap in the firearms world. Making guns out of stainless steel wasn’t as easy as changing the metal used. There was a lot of engineering that was needed to learn how to machine it, make it work and make it last. Smith & Wesson was a leader in this when they introduced the Model 60.

We take stainless steel guns for granted these days but there was a time when the only stainless 1911 to be had was made by Randall. It took some time for the mass production of stainless rifle barrels to become common. Manufactures worked for years to overcome the problem of pistol slides and frames from galling (specific alloys were the answer, sometimes even different alloys between frames and slides).

Ruger was an innovator with not only the use of cast steel but the use of cast stainless steel. Several rifle manufactures introduced rifles that are extremely well suited to harsh weather conditions.

We’ve come a long way since S&W introduced the model 60 and we now have some incredible choices.
 

Snakeoil

Well-Known Member
Not to be a nit-picker, but stainless is not hard, it is tough. That's probably a hard concept for a anyone who might not have any machine tool experience. The metal resists cutting, but cuts nicely if that makes any sense. It will also harden like glass if overheated under pressure. Perfect example is trying to drill it with a dull drill and overheating it in the process. You'll normally need a carbide bit to get thru that thin surface of glass-hard steel. Stainless also has a springiness to it that non-heat treated, carbon steel does not. This shows up in sheet metal goods and the difficulting in forming it into shapes. I remember a discussion with a guy who made vintage Triumph motorcycle fenders. He was wealthy and bought the automated forming tools to turn out fenders since the factory went belly up long ago. He said that carbon steel fenders were a snap. You put the properly shaped blank into the machine (a set of rollers) and out the other end came a perfect fender. It sometimes took a second pass for them to be perfect. But you put the same blank of stainless into the machine and something that looked like it came from a pasta factory got spit out the other end. He said it would take as many as 15 or so passes thru the machine to get a fender he could sell in good conscience.

I'd gotten in touch with him because I'd purchased one of his fenders and it was far from a drop in fit. That Triumph I posted in the Wheeled Thingy Thread has his rear fender. Between him and talking to a few Triumph resto guys that had dealt with many of these, I came to understand that to make the fender fit, I was in for a true wrestling match. I started out gently and all that thing did was laugh at me. I talked to one expert who would not sugar coat things and he said I had to truly honk on it. I had a 4 foot 2x4 clamped to the fender so that I could twist and bend it at the same time to get it to conform to the bike frame in a relaxed state. I kept track of the time it took to fit that fender and it was over 20 hours. As you can see, I won. But it was a hard fought battle.

So tough is the proper descriptor for stainless. ;)
 
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Glaciers

Alaska Land of the Midnight Sun
Not gun related but I ran vessels in the salt of Prince William Sound for many years, so stainless fasteners were only used. Small town marine supply store, and 2 hardware stores only supply of stainless bolts within 300 miles. Had for a few years bolts and screws made in the USA and nuts made in Mexico. My bitch was that the thread pitch was ever so slightly off between the two. Add that into the mix of galling and you rarely could reuse a fasteners, some would break when attempting removal. The bigger the bolt of course fewer problems. As far as rusting goes on a salt water vessel you are almost daily washing down with fresh water and scrubbing, cleaning, and brushing was a constant, so stainless rusting was minimized. Early on the stainless products really were more pure stainless as some didn’t seam to rust even in the salt conditions present.
If we did have rusting of stainless or painted carbon steel equipment there was always Osflow. I know that’s not the correct spelling but great rust remover.
Can’t speak to machining, but worked with enough stainless shafting, Aquamet 17, 19, and 22 along with plate for rudders. Used Aquamet 19 on the vessel we built in 94, had motor mount issues right from the builder. To much movement. Replaced probably 7 or 8 - 2” by if memory serves 107” long. Aquamet 19 is pretty hard or tough as you might prefer, but when that shaft had to be straight, and I mean straight so not to have vibration underway, which will cause fracturing, you checked the shaft before installing. Would take the shafts in supporting crate to John Kunick’s Machine shop120 miles up the road for final straightening before installing. John would place the shaft on two V blocks and run a dial indicator on it. If there was runout, and there was always some after overnight shipping on aircraft from Seattle with a transfer in Anchorage shafts being 9’ long and heavy even crated got beat. So John would hit a pin point spot for a second with his torch then recheck. Guy was good. He also recut propeller tapering and keyway and threads on more then one shaft for me.
As far as rust goes, I still have two broken Aquamet 19 shafts that I lost in the woods next to the shop and showed up when running the four wheeler and trailer through there, I noticed something shiny. There they where after being in the woods covered with dirt, pine needles, leaves for the past 20 years. The wooden crate was pretty much rotted away and keep in mind they had years of use in salt water. Not one speck of rust. The rudder platting would tarnish with a light rust though.
Had one vessel with Aquamet 17 shafting and rebuilt my last vessel with Aquamet 22 because of the increase in horse power and torque with the new diesel replacements. Aquamet 22 is tough stuff.
 

Rick H

Well-Known Member
We tend to lump stainless steels together like it is all the same. It is not. Most 400 series stainless will discolor readily but is reluctant to rust through. (modern automobile exhaust systems, turn a dirty brown gray color but don't rust out). Then there are non magnetic 300+ series of stainless steel that are very slow to discolor. The physical properties, resistance to corrosive substances and heat vary. It is better to break down each grade of stainless and consider them as a separate and different materials because they are.

I spent 6 years working in a small machine shop making aircraft engine parts of various exotic materials. Each grade of SS took a different set up of drill angles and chip relief, speeds and feeds to machine. Some work hardens, and some not so much. The engineers specified materials for various parts for the different physical properties needed to keep them functioning for as long as possible in the hostile environment of an afterburning jet engine.
 

Snakeoil

Well-Known Member
If you read that article I posted, I suspect that passivation might be the reason that some of those stainless applications did not rust. Just thinking out loud here. I knew guys at work that worked in our materials lab and they all had PhD's in metallurgy and such. I loved taking a problem to those guys. It was always such a great learning experience. And they had all these neat tricks to identify problems that were pretty much invisible. Our gas turbine compressor blades were NiCad plated to protect from corrosion. But the Cad would deplete as part of the protection process, leaving the nickel behind. Nickel is porous and corrosive contaminant (like salt in the Caribbean) could get into those pores and eat at the base metal under the plating until the pit was big enough to create a stress riser which would cause a crack to form and one day, the unit would swallow a blade and corn cob the compressor. One of my buddies in the lab had this stuff he called "fast iron solution". It would turn blue (maybe purple as I'm red/green colorblind) in the presence of iron. A customer would have a unit open and the blades looked fine. I knew that with the hours on the machine and the ambient conditions, the Cad was gone and the blades were ticking bombs. The customers would never believe me. I'd demo the solution on a piece of steel and then go over to their blades and it would reveal the pours in the nickel and the pits that were growing out of sight. It was like being a magician. Occasionally they would still not believe me and would pay the price within a year or so. Then they would have me come back with my magic sauce to check all their other machines. God, I miss those days. Although, today, I probably could not have that little bottle in my briefcase on a plane.
 
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smokeywolf

Well-Known Member
Electropolishing will also reduce or delay corrosion. Polishing in effect, knocks down high spots on the surface thereby reducing surface area, which in-turn reduces exposure to corrosive elements or atmosphere.

In the motion picture film laboratories, depending on the chemical in each tank of a high speed film processor, either type 316 stainless was used for tanks, shafting, fasteners, film sprockets, etc. Or, titanium or occasionally Hastelloy C. Even titanium would eventually break down in the bleach tanks, but Hastelloy C would outlast them all. It still was not used much because it's at least as difficult to machine as Inconel, Invar, Kovar, etc.
 

Petrol & Powder

Well-Known Member
As a material for firearms, Stainless Steel has some real advantages, but it also has some critics.

From a weather resistance point of view stainless steel is a huge improvement over blued carbon steel. For a carry gun that is exposed to sweat, rain, snow, etc., stainless is a plus. And there’s no doubt that stainless will tolerate a bit more neglect than a blued finish.
There are some folks that claim the action of a stainless-steel DA revolver will never be a smooth as the same action in carbon steel. I’m not sure I believe that.
And there are some complaints about the light reflecting quality of polished stainless steel but that is easily corrected with a different finish.

In 1965 Smith & Wesson introduced the model 60, the first mass-produced stainless-steel firearm. In 1975 Ruger introduced the stainless-steel Security-Six (followed by the Service-Six and Speed-Six). Ruger also used stainless steel for the many of the internal parts of their DA revolvers, even if the gun was a blued steel model. In 1977 the AMT Hardballer was sold as the first all stainless 1911 style pistol, but production was a bit iffy. In 1982 Randall made their first stainless steel 1911 style pistol.

Today, stainless steel guns are extremely common but that hasn’t always been the case.
 

JustJim

Well-Known Member
In 1977 the AMT Hardballer was sold as the first all stainless 1911 style pistol, but production was a bit iffy. In 1982 Randall made their first stainless steel 1911 style pistol.
Guns like the Hardballer are part of the reason some folks are skeptical of stainless handguns. Aside from the QC problems, or the "unusual" way they made the barrels, many folks who shot one much ran into problems with galling.
 

Petrol & Powder

Well-Known Member
Guns like the Hardballer are part of the reason some folks are skeptical of stainless handguns. Aside from the QC problems, or the "unusual" way they made the barrels, many folks who shot one much ran into problems with galling.
Yep, no doubt.
The galling issue on pistols took a while for the industry to fix. Ultimately the answer was finding the correct alloy (or sometimes alloys with a different alloy for the slide and frame).
The bias against DA revolvers seemed to be more about disturbing tradition more than actual performance issues.
 

Snakeoil

Well-Known Member
Yep, no doubt.
The galling issue on pistols took a while for the industry to fix. Ultimately the answer was finding the correct alloy (or sometimes alloys with a different alloy for the slide and frame).
The bias against DA revolvers seemed to be more about disturbing tradition more than actual performance issues.
I have a stainless Mod 60 that belonged to an Albany detective. The frame had some small pits on the side that was against his body. I'm sure sweat was the primary cause. Made new grips that covered that area. But the important hammer/trigger parts are all carbon steel.
 

Petrol & Powder

Well-Known Member
S&W went through a lot of iterations when it came to stainless steel guns. Stainless steel sights vs. carbon steel. Triggers and hammers that were flash chromed, carbon steel, MIM, and stainless and probably a few variations I missed. Michigan State Police even issued a Model 38 with a stainless-steel cylinder.
 

RBHarter

West Central AR
If 75 is accurate for Ruger and SS my Sec 6 might have been a collector piece as the SN dates it mid 74'