460 XVR marks on Cylinder Face

[Hoogs]

Hi all...

Just been cleaning the cylinder face on my 460 XVR and noticed some marks between each chamber and the edge of the cylinder on 4 out of 5 chambers. They look like cracks or fractures in the steel, however I have only fired about 50 rounds through it since new. (and most of them were .45 LC due to unavailability of ammo).

Just wanted to know if anyone else has similar marks on their cylinder face, and/or get some opinions...


Cheers

 

[MichiganScott]

Slight gas cutting/burn marks that probably lines up with the top of the barrel leade. I'm betting the barrel is not quite square with the cylinder and a bit more gas escapes from the top leaving the mark. If it's actual cutting, it will be self limiting.

 

[Hoogs]

Brand new gun, 90% of shots fired being from .45 LC... Less than 50 shots total....

If the "crack" was visible on all chambers i'd say it was normal.... but it's not...

I'm just after some advise as a proud new gun owner... we all hate seeing imperfections in our new toys.... i Just want to make sure that with such a robust cartridge, this doesn't pose as a safety concern....

 

[scooter123]

Sometimes Cold Drawn Steel can develop "laminations" in the raw steel due to imperfections. In round bar stock that can show up as circular inclusions in a section of the bar. However, these are usually partial or full circles and would NOT be oriented with the chamber positions on a finished cylinder. I'm thinking that what you are seeing may be a bit of gas cutting and the reason why it's limited is likely due to a very slight variation in the Barrel/Cylinder gap do to an off square cylinder face. My theory is that this gas cutting is a cavitation type interaction event that is VERY dependent on the B/C gap being exactly "wrong", so much so that a change of only 0.0003 or 0.0004 inch is make or break for this to happen. However, this is just a hunch and IMO you should contact S&W and have them take a look at your pictures because I could be wrong.

BTW, if this is due to cavitation in the B/C gap changing bullet weight or to a different velocity loading will probably cause this to change. What I suspect is happening is that a microscopic Standing Wave is being setup in the B/C gap and that is what is causing this erosion.

 

[Hoogs]

Thanks guys, I appreciate your advice

 

[ms]

Cavitation...

...My theory is that this gas cutting is a cavitation type interaction event that is VERY dependent on the B/C gap being exactly "wrong", so much so that a change of only 0.0003 or 0.0004 inch is make or break for this to happen. However, this is just a hunch and IMO you should contact S&W and have them take a look at your pictures because I could be wrong.

BTW, if this is due to cavitation in the B/C gap changing bullet weight or to a different velocity loading will probably cause this to change. What I suspect is happening is that a microscopic Standing Wave is being setup in the B/C gap and that is what is causing this erosion.

As I try and think back a decade or three, I remember cavitation as being an event that involves gas bubbles in a liquid. Is my recollection out of date or faulty, or is there liquid in the OP's revolver?

 

[ms]

reference, please

I'm afraid your recollection is only partially correct. The "gas bubbles in a liquid" is just a symptom of cavitation. An aircraft propellor can cavitate, and lose thrust in the process, also. Has nothing to do with it being in water or air etc and has everything to do with flow.

I looked around for several minutes, and can find nothing to support your definition. Please provide a reference for an aircraft propellor (in air) actually cavitating, or for cavitation to occur without phase transition.

 

[Hoogs]

Thanks for advice. It is one of 2 things causing the marks I'm now thinking... Gas cutting or cylinder contacting forcing cone. Either way, I don't feel as though it should be occurring in a brand new gun with so few rounds fired... And no hot loads. Have contacted S&W... Now playing the waiting game for a reply.

As for cavitation, my understanding in relation to liquids is that it is the formation of vapor bubbles (technically water "boiling") on the inlet side of a pump / propellor due to a decrease in pressure, and these vapor bubbles imploding once pressure increases in the volute of the pump, or as they travel through the prop...

Cheers again

 

[Hoogs]

Problem identified...

Upon close inspection (magnified) the marks all appear to have a number of vertical indentations coming off them, and all in the same place. After cleaning up the forcing cone, it appears as though the Cylinder Face has been coming in contact with the top inner edge of the Forcing Cone under recoil, and the marks have been "stamped" on the Cylinder Face...

Just heard back from local distributor who informed me:

"it's caused by something referred to as 'end shake' and is perfectly normal in S&W revolvers..." ​

Really? with 45 LC ammo?? I wouldn't expect that was normal even with full 460 S&W loads... Contact hard enough to stamp the steel has to be causing damage and stress

Anyway... They have said they will look at the cause, repair it, then polish the gouges out of the Cylinder Face...

 

[tomcatt51]

As for cavitation, my understanding in relation to liquids is that it is the formation of vapor bubbles (technically water "boiling") on the inlet side of a pump / propellor due to a decrease in pressure, and these vapor bubbles imploding once pressure increases in the volute of the pump, or as they travel through the prop...

Yes, we're dealing with definitions. In water, a prop or impeller cavitates. In air, a propeller stalls.

 

[Hoogs]

I just wanted in on the discussion

 

[MichiganScott]

Upon close inspection (magnified) the marks all appear to have a number of vertical indentations coming off them, and all in the same place. After cleaning up the forcing cone, it appears as though the Cylinder Face has been coming in contact with the top inner edge of the Forcing Cone under recoil, and the marks have been "stamped" on the Cylinder Face...

Just heard back from local distributor who informed me:

"it's caused by something referred to as 'end shake' and is perfectly normal in S&W revolvers..." ​

Really? with 45 LC ammo?? I wouldn't expect that was normal even with full 460 S&W loads... Contact hard enough to stamp the steel has to be causing damage and stress

Anyway... They have said they will look at the cause, repair it, then polish the gouges out of the Cylinder Face...

The distributor says they will take care of it instead of sending it to S&W? I have visions of a local kid in the shipping department taking a Dremel and a mill file to your revolver and increasing the cylinder gap enough for mice to build a nest in the forcing cone.

It's obvious that you don't believe their explanation. Call S&W's customer service and they will send you a call tag.

 

[Hoogs]

Just been thinking... Do you think that firing such a Revolver as the 460XVR in a Ransom Rest could cause this?

That maybe due to the un-natural recoil in which it allows the barrel to flip up, but not the gun to actually move backwards would be causing enough stress that the cylinder would collide with the forcing cone?