How to stop gas cutting?

[WestKentucky]

Gas cutting, the abrasive blast of hot gas and burning powder that escapes from the BC gap. How do you stop it on the big boomers? I find myself suddenly concerned due to the acquisition of the 46000psi pipsqueak .327 fed mag, and the constant interest in a 357 max.

The engineer in me wants to look logically at the problem and detail out a solution. The issue is, that the problem has been a problem since the end of the 19th century when hot-rod rounds like 32-20 and 38-40 were chambered in the earliest cartridge revolvers. Now we are looking at huge numbers by comparison, along with different metallurgy, different powder, and different manufacturing technology. So not only is there the problem of designing it out, but also of fixing the current design to minimize the problem.

So looking at flame cutting. There are some obvious points.
1. The gas escapes via BC gap at the highest pressure and hottest point. Also has pressure escaping for the duration of the shot.
2. The larger the gap is, the more escapes. Small gaps are optimal to minimize cutting, but small gaps and carbon buildup are known to lock up guns. Seems this in an of itself says that we should find a happy medium and stick to it.
3. Flame cutting happens on the topstrap of a traditional revolver. Assumed that with an upside down gun like a Chiappa rhino it would happen along the lower portion of the frame.

Some things to consider would be...
Distance between frame and chamber
Metallurgy on the frame
Inserts into the topstrap (replaceable, or more durable)
Powder grain size
Powder burn rate
Cylinder design
Frame design
Forcing cone design
Historic models that managed to avoid cutting by one means or another (open top colt has no strap to cut, nagant seals gap).

What am I missing?
Has anybody legitimately made a revolver with a sacrificial hardened plate?
Has there been a frame feature designed to deflect and minimize cutting? Could those features be added to current guns, or current designs?

Armchair engineers, let’s figure this one out.

 

[adcoch1]

A sacrificial plate is probably the best idea, but it'll be ugly. Also it is a self limiting issue, as the cut gets about 3/16 away from the gap(in a 44mag) it no longer can cut. So theoretically a 6shot 327 mag in a Redhawk probably wouldn't hurt the top strap at all. It would just weigh 11 lbs....

 

[Drail]

That's true. Once the cut goes so far the now curved cut acts like a Jai-alai racquet and redirects the gases off to the sides. Once it reaches that point no more cutting takes place. The problem solves itself - but you will lose a little bit of metal. It's the price you pay for playing with magnums. All of my magnum revolvers showed flame cutting early on and then stopped.

 

[MikeInOr]

Sounds like someone needs to take into account the shape of the flame cut strap after it is no longer able to be cut then design a strap around that shape so the flame cutting never starts.

 

[NIGHTLORD40K]

A ceramic insert perhaps? Or something akin to the heat resistant tiles on reentry vehicles? Maybe even a version of Chobam/Burlington armor plate which is specifically designed to resist HEAT (shaped charge) anti tank rounds?

I'm sure it could be done at some astronomical price, but, as Drail said, modern metallurgy has really made flame cutting little more than a cosmetic issue at this point.

 

[Saleen322]

We have both a 357 Super Mag and a couple of 327 magnums. The 357 SM was my silhouette revolver when I competed in the 80s. If you don't want a flame cutting problem, refrain from shooting light bullets. In the 357 SM that means 180 grain and heavier should be used. The bullet loaded the most in our 327s is a 132 grain and I seen no cutting. I can't tell you how many rounds are through the 357 SM but it still shoots 2" groups at 50 yards. It is common to get some cutting but it only goes a couple of thousandths and then stops. Look at a 357 mag that has a lot of 125 grain or 110 grain magnums though it. You will see cutting more so than one that had 158s and heavier shot through them. YMMV

 

[bersaguy]

I recently bought my 1st revolver and was thinking the same thing. I wonder why the action was never made in such a way that the cylinder moves forward to seal aginst the barrel. Imagine a chamfer cut on the outside diameter of the forcing cone and a matching chamfer on the inside diameter of the cylinder chambers, or vice versa. Now, this would probably make for an extremely heavy double action trigger, and require some very fine machining, but should contain the combustion gasses. The general concept was developed 300 years ago...

 

[BobWright]

This Ruger Blackhawk has, as shown, over 20,000 rounds fired through it, many very high performing handloads:



This Super Blackhawk, .44 Magnum, has just over 17,500 rounds, all full magnum velocity:



This .357 Magnum also over 17,000 rounds fired:




Is gas cutting a problem?


I think not.


Bob Wright

 

[BobWright]

Gas cutting, the abrasive blast of hot gas and burning powder that escapes from the BC gap. How do you stop it on the big boomers? I find myself suddenly concerned due to the acquisition of the 46000psi pipsqueak .327 fed mag, and the constant interest in a 357 max.

The engineer in me wants to look logically at the problem and detail out a solution. The issue is, that the problem has been a problem since the end of the 19th century when hot-rod rounds like 32-20 and 38-40 were chambered in the earliest cartridge revolvers. Now we are looking at huge numbers by comparison, along with different metallurgy, different powder, and different manufacturing technology. So not only is there the problem of designing it out, but also of fixing the current design to minimize the problem.

So looking at flame cutting. There are some obvious points.
1. The gas escapes via BC gap at the highest pressure and hottest point. Also has pressure escaping for the duration of the shot.
2. The larger the gap is, the more escapes. Small gaps are optimal to minimize cutting, but small gaps and carbon buildup are known to lock up guns. Seems this in an of itself says that we should find a happy medium and stick to it.
3. Flame cutting happens on the topstrap of a traditional revolver. Assumed that with an upside down gun like a Chiappa rhino it would happen along the lower portion of the frame.

Some things to consider would be...
Distance between frame and chamber
Metallurgy on the frame
Inserts into the topstrap (replaceable, or more durable)
Powder grain size
Powder burn rate
Cylinder design
Frame design
Forcing cone design
Historic models that managed to avoid cutting by one means or another (open top colt has no strap to cut, nagant seals gap).

What am I missing?
Has anybody legitimately made a revolver with a sacrificial hardened plate?
Has there been a frame feature designed to deflect and minimize cutting? Could those features be added to current guns, or current designs?

Armchair engineers, let’s figure this one out.

 

[BobWright]

WestKentucky asketh:

Has there been a frame feature designed to deflect and minimize cutting? Could those features be added to current guns, or current designs?

This:






Bob Wright

 

[cheygriz]

Since it's going to stop at a certain point, why worry about it????

 

[jamesjames]

The Smith 329 PD (Airlite, scandium aluminum frame) has a sacrificial flame cutting shield (stainless) mounted into the top strap above the cylinder gap.

 

[RetiredUSNChief]

Speaking as an engineer myself, if you want to eliminate gas cutting you will have to eliminate the gap between the cylinder and the barrel at the moment of firing, and up until the point where the pressure in the barrel/cylinder drops below whatever pressure threshold would cause cutting.

So long as there is a gap, there WILL be gas cutting. Even if you beef up the components like the backstrap or the steel of the cylinder and barrel in the vicinity of the gap, gas cutting will STILL occur...maybe at a reduced rate, but it WILL occur. You have to STOP the flow of gas between these components if you truly want to eliminate gas cutting.

It seems to me that there might be a way to re-engineer the revolver to allow the cylinder to "cam" along the cylinder pin such that the cylinder will move forward and mate/seat with the barrel to eliminate the gap when the hammer is fully cocked, or just before the hammer is released when the trigger is pulled on double action revolvers.

Then, as the hammer is cocked back for the next shot (either by single action or double action), the cylinder "releases", slides back fractionally, then rotates to the next shot. Or, alternatively, the cylinder releases for this act immediately after the pressure drops and before the hammer is cocked back for the next shot.

HOWEVER...there are problems with this. Not necessarily insurmountable, but problems nonetheless.

This increases the mechanical complexity of the revolver, which necessarily increases the number of things that can go wrong. It may also increase the weight of the revolver a bit in the effort of engineering a system with components robust enough to withstand a lifetime of operability.

And, as we all know, increasing the mechanical complexity has an inverse effect on mechanical reliability. Revolvers are inherently the most reliable multi-shot handgun design BECAUSE of their simplicity. So the question is "Would the benefits of re-designing the revolver to eliminate gas cutting be worth the cost in terms of maintenance and reliability?"

 

[cheygriz]

The moving cylinbder has been tried.


www.wikipedia.org/wiki/Nagant_M1895

 

[silicosys4]

Is gas cutting a problem?


I think not.


Bob Wright

YMMV

While not a problem, this well used 586-1 I picked up a few years ago has definitely seen whatever combination of powders, velocity, and bullet weight is necessary to cause gas cutting.

 

[shooter1niner]

Perhaps a larger radius in the corner combined with a metallurgical upgrade or a localized spot heat treatment. The larger radius would most likely redirect hot gasses not allowing them to blowtorch into a sharp corner. Just some thoughts...

 

[Vern Humphrey]

View attachment 804399

YMMV

While not a problem, this well used 586-1 I picked up a few years ago has definitely seen whatever combination of powders, velocity, and bullet weight is necessary to cause gas cutting.

Well, that's the point. No one says gas cutting doesn't happen, only that it stops before it becomes a problem.

 

[243winxb]

A removable blast shield for a firearm.
Smith and Wesson patent.

https://patents.google.com/patent/US6330761

 

[Monac]

Has anybody legitimately made a revolver with a sacrificial hardened plate?

I have a vague memory of such a thing in a 357 Maximum revolver, where the gas-cutting issue came up in a big way about 30 years ago. I want to say Ruger or maybe Dan Wesson, but frankly I cannot be sure I saw such a thing at all, let alone what kind of gun it was in.

 

[daverich4]

Gas cutting, the abrasive blast of hot gas and burning powder that escapes from the BC gap. How do you stop it on the big boomers? I find myself suddenly concerned due to the acquisition of the 46000psi pipsqueak .327 fed mag, and the constant interest in a 357 max.

The engineer in me wants to look logically at the problem and detail out a solution. The issue is, that the problem has been a problem since the end of
What am I missing?
Has anybody legitimately made a revolver with a sacrificial hardened plate?
Has there been a frame feature designed to deflect and minimize cutting? Could those features be added to current guns, or current designs

Armchair engineers, let’s figure this one out.

My M&P R8 has a flame cutting shield.

 

[crestoncowboy]

I think all of the scandium frame Smith and Wesson magnum guns have a removable shield. I know my 329s do

 

[Riomouse911]

If I recall correctly:

Ruger discontinued the .357 Max Blackhawk due to flame cutting concerns.

DW supplied an extra barrel with their 8” .357 Supermags because of shooters fears they would wear quickly.

The Maximum is a very high-intensity round that was (is) tough on revolvers. But I’d still like to own and shoot one someday....

Stay safe!

 

[Jonesy814]

I think all of the scandium frame Smith and Wesson magnum guns have a removable shield. I know my 329s do

Yes, I am pretty sure all vanadium framed S&W revolvers have a Shield. My friends 360j which is only a 38 special even has one

 

[BobWright]

I made the post of the Open Top as a means to reduce gas cutting with tongue-in-cheek attitude, but I have discovered one advantage to this design.

Note the barrel stub right in front of the cylinder:



This rounded surface deflects the blast forward. While the upward flash is distracting at times, I've noticed that soot and bullet lube don't tend to build up on the cylinder, hence my hands stay cleaner when firing this little gem.



And little gem it is. Accuracy is nothing to write home about, but this thing is just plain fun to shoot!

Bob Wright

 

[reddog81]

If you don't shoot the gun you never have to worry about gas cutting...

Like others have mentioned for the most part it's self limiting so realistically it doesn't matter. My 45 ACP S&W 325PD has a shield to protect the scandium frame. The Nagant revolver also eliminates the gas cutting problem but for some reason it requires a 15 pound trigger pull to move the cylinder forward and seal the bore.