Cylinder Throat Machining ??

[scruffy]

What are these machining marks on the cylinder throats, (the rings at 12 and 8 o'clock, not the chamfers)? Tooling? Not my gun but have seen this now on several new S&W revolver cylinders. If the purpose of the throat is to help size the bullet for the forcing cone and bore and typically has a smaller diameter than the bullet, I would think this would act like a cheese grater on lead or copper jackets.

 

[armorer951]

While I'm certainly not a machinist, and I'm not sure about the scratches or machine marks on the interior of the chamber, I've never seen a cylinder bore countersunk like that....or to that extent. Also, some very obvious chatter marks present on this angle surface or countersink that don't appear normal to me for sure. (not factory)

Perhaps the marks inside the chamber came from the pilot of the tool used to create this abnormal "countersink"?


Carter

 

[Protocall_Design]

You want the throats to be bullet size to .001 larger. The bullet should not get sized down until it hits the barrel. Every part of the chamber should be smooth. The cheese grater parts are not good. If the throats are undersized (not likely), they could be reamed to size and smoothed out that way.

The chamfers on the throats are not good, either. You want the corners of the throat and forcing cone holes as square and sharp as possible. Having chamfers on the holes allows a lot more gas leak at the cylinder gap.

If that were my gun, I'd be shopping for a new cylinder.

 

[stansdds]

That is some pretty crummy machining. This is why I recommend people closely inspect any firearm before accepting it.

 

[toad67]

Almost looks like the two bottom holes don't have the marks.

 

[scruffy]

Almost looks like the two bottom holes don't have the marks.

Camera is out of focus on the other holes.

 

[Bullseye Smith]

Looks like you need a new cylinder.

 

[series guy]

My first question is how does the gun shoot?