Used Smith M27 price check and flame cutting

[Dr. Dave]

I just picked up a used 8 3/8" M27-2 (pinned + recessed) in excellent
condition. It has a hogue monogrip on it and did
not come with the box. There is the beginning of
a drag line on the cylinder, but no other bluing
wear except the slightest amount (barely noticeable)
at the muzzle. It is really tight and the rifling is sharp. I paid 350 for it. Serial number N186XXX. Any idea when
it was made?

I did notice that it has what appears to be factory
tapped holes under the rear sight. Is this normal in
a 27-2? I thought this was only done on late model
stainless guns.

One thing that is disconcerting is a line that I thought
fouling near the forcing cone on the topstrap. I can't
feel it with a small metal wire, but it won't clean
off. It does not I assume this is flame cutting? How bad is this,
and how much usage is required to get it to this state?

Thanks

 

[Dr. Dave]

looked some more

I scrubbed it some and checked with a flashlight. It definitely looks like there is pitting in the metal along the line, but it doesn't extend past the end of the strap (not along the sides). it definitely isn't deep.

 

[Good Guy]

If it's so minimal that you need a flashlight to see the flame cutting of the top strap, don't worry about it. It'll take a whole lot more shooting to increase the cut to any degree.

You could check the B/C gap, .004" to .007" is ballpark. If it's a lot more than that, it can contribute to gas cutting over a long period of time.

I've got one old S&W that has flame cutting to at least 1/3 the thickness of the top strap. Looks bad but it still gets shot occassionaly. I can only imagine the THOUSANDS and THOUSANDS of hot loads it must have took to cut the strap that much. I don't worry about it. Relegated it to home defense use. Seems like a fitting retirement for a senior sixgun.

 

[sw627pc]

N186xxx would have been made in the 1972-74 time frame, probably closer to 74 than to 72.

Flame cutting on the topstrap is normal on these guns if they've been shot very much. Normally goes so far and stops. Just about any .357, of any brand, that I've ever looked at that has had very many full loads fired in it exhibits some amount of cutting. As long as the forcing cone isn't showing erosion you don't have a problem. Very hot loads will eventually ruin the forcing cones, this can create some dangerous situations (this effect was what pretty much killed the .357 Maximum cartridge). I've seen very early S&W .357 guns (pre war mostly) that were fired with the 1930-40's loads (hotter than modern loads) that are showing some erosion of the forcing cone. I haven't seen any post war N frames that have a problem at all.

 

[jimmy]

Congrats on your acquisition! I'm not usually a fan of 8 3/8-inch barrels, but the Model 27 is definitely an exception.

 

[Phil in Seattle]

NOw this is a really relevant topic to me.

Today I picked up a used 27-2 also. Serial # N408XXX pinned and recessed. From the description it has a bunch more wear than Dr. Daves does, mostly at the muzzle and the front of the frame. I got the 6" barrel though.

It wasn't on my list of things to look for but I saw it and had an instant flashback to years ago when I was shopping for a Model 27. Since that time I hadn't thought about getting one until today

Now to get all of this old oil off of it and get a nice coat of renaissance wax on it.

 

[John Lawson]

Flame Cutting

If you read up on internal ballistics, you'll find that the gases from combustion do not get hot enough to flame cut steel. What you are seeing on the top strap is the sandblast effect of unburned powder granules assailing the top strap in the position of the barrel/cylinder gap. If you want a reference to internal ballistics and peculiarities, read "Chemistry of Powder and Explosives" by Davis, reprinted by Wolfe and usually available from gun book sellers at gun shows or Ray Riling Arms Books in Philly.
If you want to stop this cutting action dead in its tracks, or prevent it on other revolvers, you can take two routes. In the old days, every magnum revolver shooter obtained a carpenter's pencil...the one with the rectangular lead... and put a coating of graphite on the top strap after cleaning. These days, a coating of dry moly disulphide lube will accomplish the same thing. So will going to a faster burning powder of the flake type. Spherical powder makes a very efficient bead blasting medium. If you check up on internal ballistics of your load on a computer program, you will find that a lot of unburned powder follows the bullet. Setting up a large sheet of plain white paper downrange about 15 feet will also show up burn marks from unconsumed powder granules when you shoot.

 

[James K]

Somewhere I have a letter from S&W saying that the cutting never gets deep enough to be of concern or to endanger the gun or shooter. They called it flame cutting.

I have not read that book, but do not believe the writer is correct. Hot high pressure gas directed through a narrow gap will certainly cause cutting, where unburned powder grains are far too soft to have a "sandblast" effect.

As to gases from powder combustion not getting hot enough to cut steel, that is exactly the cause of erosion in rifle barrels, and also of erosion in pistol barrels (like the .45 auto) when a bullet jacket does not fill the grooves and gas escaping past it erodes the edges of the groove.

S&W used to deal with top strap flame cutting by milling a small dome shaped cut into that area, but they dropped it as a cost reduction measure when they found it was not needed.

Jim

 

[John Lawson]

Flame Cutting is a Myth

During a hurricane, the high winds have been known to drive soft straws through the trunks of hardwood trees. It is is VELOCITY and not the softness of the driven object.
If you read a book on acetylene welding (the part about cutting with a torch) and note the temperatures required, then read the book on powder and explosives and note the temperatures involved, it becomes plain that there is not flame cutting.
The damage done to cheap .22 rifles having mild steel (carbon steel) barrels that have fired lots of .22 shorts right in front of the short case is due to repeated heating and cooling of the steel, resulting in oxidation (rust.) The shooters did not believe in cleaning their rifles, having shot "Kleenbore" ammo that was advertised as not requiring cleaning afterward. When the rust residue was finally knocked out of the chamber, there were rust pits in an annular ring at the front of the short case, right where the heat of combustion was greatest.
It is completely unsafe and foolhardy to blow 296 powder through a portable sandblaster, but if (I said IF) it were done it would clean rust off a steel plate as effectively as "hard" glass beads. And that is at only 100 psi. Think of the mayhem at 33,000 psi.!
Check this out with a physicist, an engineer, a metallurgist and a ballistics engineer. I have. And so, I say that flame cutting is a major misnomer on the part of people who have jumped to a wrong conclusion. Actually, I still have the article I wrote on this "Flame Cutting Myth" over 20 years ago in AH.
Drop by. If you can prove I'm wrong, I'll buy the lunch. Otherwise, its your turn.

 

[Long Path]

Interesting concept.

Jim, I've always bought "flame cutting" as the gospel truth, but... so help me, John's words make some sense, here...

Now, does the aforementioned PRESSURE change the temperature neaded to "cut" steel? In effect, pressure will change the amount of heat entering a given object over a given time.

L.P. , (who's working out Charles' Law, Boyle's Law, Bernouli's Principle, and which was the prettiest Angel...)

 

[sw627pc]

Most properly it should be called high pressure gas erosion. And no powder flakes or residue are really needed, anyone who has ever worked with high pressure steam (superheated) in a Navy ship's boiler room will tell you that a small leak can cut steel quite quickly. Not hot enough to do anything, but the high pressure/velocity even of a gas will erode just about anything. My experience with these guns is that the erosion doesn't go very far, once it gets to a certain depth it stops, probably because the high velocity gas is loosing enough velocity in the distance traveled to stop eroding the steel.

 

[Phil in Seattle]

I think I might be catching some sort of bug.
Here it is a month later and another M27 has found it's way home with me.
This one is also a 27-2 but it's the 3.5" barrel, the serial number is quite a bit lower too at N162XXX.
Minor worn spots at the front of the under lug, a few rust scratches on the trigger guard, and a few rust spots on the back strap and grip frame where the Pacmayr grips had covered it up and on one thought to take them off and put anything on to protect the finish.
It's a real handful of gun that's for sure.

Is there hope for me or must I begin a quest for an 8 3/8" & the 5 1/2"? version too?