"Ring" inside S&W 67 cylinder chambers?

[A strange person]

I just bought a new S&W 67. It is my first revolver. I have only fired a few dozen rounds through it so far. Upon cleaning it for the first time, I noticed that there were black rings inside the cylinder chambers (about 2/3 of the way down looking in from the back). I assumed it was just acute fouling from where the bullet leaves the case mouth, and cleaned the chambers with solvent and a brush. The rings were still there after, except now they did not look like fouling, but more like engravings. Does anybody know what this is?

 

[rcmodel]

Yep.
The case is larger then the bullet inside the case.

Its where the chamber that fits the case ends and steps down to the chamber throat that fits the bullet.

In a .38/.357 the chambers measure .380" and step down to nominal .357" throats.

rc

 

[A strange person]

Thanks.

I should have been able to have guessed that. I think I am getting dumber.

 

[J2FLAN]

On the `67, the "ring" is were the case mouth stops in the cylinder, when you touch the round off, the black ring is from the gass and powder at the case mouth when the bullets leaves it. Very easy to clean so it will shine like the rest of the cylinder charge hole, unlike 357s that shoot 38s.

 

[MrBorland]

As RC indicated, these are the throats. The throats stabilize the bullet before it leaves the cylinder and enters the forcing cone. Properly-sized throats are important for good accuracy. Too big, and the bullet enters the forcing cone askew. Too small, and the bullet is swaged down too far and rattles on down the barrel.