cylinder vs barrel reamers

[matthias]

here we go
what is the difference ( specifically ) between a barrel reamer and a cylinder reamer for a revolver?

i am assuming it is the throat that is different

i am having a hard time visualizing it. and i have a bat poop crazy customer that wants some weird stuff built. so exploring possibilities i am , thank

 

[swd]

The exit on a cylinder stays at right around bullet diameter the entir way out. The throat called a forcing cone on a revolver is cut in the barrel. So a reamer for a revolver is straight bullet diameter or slightly larger from the front of the case on forward, no tapered throat.

 

[matthias]

Understood the front of the chamber is more of a passage or bullet guide no squeeze . Fair enough thanks

 

[jepp2]

Understood the front of the chamber is more of a passage or bullet guide no squeeze

Well, I view it slightly different. There is a transition from the diameter of the cartridge to the exit diameter of the chamber (called the throat). Since jacketed bullets and lead bullets are different diameter, the diameter of throat might be wrong for the bullet selected. If the throat is sized for jacketed bullets, it will reduce the diameter of lead bullets too much and will result in leading in the barrel. So throating reamers are used to enlarge the throats to avoid this problem. And the lead bullet will tend to bump up in diameter during firing and it's path as it exits the cylinder.

The forcing cone which is cut into the entrance of the barrel is to allow for minor misalignment of the cylinder openings to the barrel entrance during firing. Timing isn't perfect when new, and as wear occurs greater misalignment occurs. This helps the bullet get started correctly into the barrel. Different angles are used for different bullet types (lead vs. jacketed).

 

[matthias]

jepp2 - so how does one decide the "correct" diameter for the throat area of the cylinder ?

 

[jepp2]

so how does one decide the "correct" diameter for the throat area of the cylinder

If you are going to shoot mostly jacketed bullets, just check to make sure a jacketed bullet will pass through the throats with just finger pressure. Most will.

If you intend to shoot mostly lead, slug the barrel with an oiled pure lead object. I use muzzle loader balls as they are pure lead and can be obtained in different diameters. Take the slug from the bore and it should pass through the throats with just finger pressure. If it doesn't it is going to lead your barrel. This is easier than trying to measure the slug then measure the throats. Most folks don't have the proper tools to do this. Everyone can slug the barrel and check the cylinders.

Some models of revolvers are known to have undersize throats. I use Manson throating reamers and they work very well.