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Old May 6, 2013, 10:45 AM   #20
Senior Member
Join Date: October 12, 2012
Location: Wyoming
Posts: 337

haven't figured out how to quote

Almost all BP revolvers are designed with an opening smaller than the rear of the chamber. This is what I said in first post.

No, they aren't. Is what somebody said in response

Quote: This is part of what I said
The smaller opening, causes the ball to be squeezed and compressed into the cylinder. Causing a friction fit.
this is what you said.
IF the openings were actually smaller than the throats, which they aren't, the ball would be swaged to the diameter of the opening and then be LOOSE further down inside the chamber where the diameter would be larger. Lead balls don't expand to fill up the extra space available in a larger diameter cylinder. There would be no 'friction fit' because the ball diameter would be smaller than the diameter of the cylinder throat. Because the loose ball would not seal the chamber, expanding gas would escape around the ball resulting in low velocity.

I did not say all.
But most are.
If you will remove your cylinder.
Then look down into it. Most of them (not all) you will see a distinct line about 3/16" or so in.
This is where the powder area has been bored slightly larger than the opening.
Some are a gradual enlargement and thus no distinct line.
Some are the same size all the way down.
I know this from personal observation and the use of a split ball gage, because over the
years I have owned many different types and models and brands.
Many of them I have bored the powder area larger myself on my lath / boring machine.
We are not talking about the throat / forcing cone at the beginning of the barrel right in front of the cylinder.
On the cylinder regardless of caliber size. the opening needs to be 2 to 6 thousands smaller than the ball you are using. Or reverse that. The ball needs to be 2 to 6 thousands larger than the cylinder opening.
When pressing a ball down into the opening several things occur and are accomplished.
1. the ball is squeezed to fit the opening thus elongating it.
2. a thin ring of excess lead is shaved from the largest diameter of the ball
3. this causes a friction / pressure fit.
4. this friction fit, causes the gas pressures to build up to a point where Newtons law
comes into effect.
Since the pressure fit of the ball is a weaker point than the rest of the cylinder, the gases push the ball out of the cylinder and down the barrel.
In normal loading the greatest diameter of the ball does NOT go below the narrower area of the opening.
Many shooters use small powder loads and then fill the chamber with filler (corn meal, fiber wads, etc). But a properly loaded cylinder will keep the ball in the immediate opening area. recessed just below the surface.

In my 44 Remmington (35 years old), I can load as little as 20 grains FFFg and the ball will be in the constricted area. I can load a max of 35 grains FFFg and the ball will be below the surface.
38 grains and the ball protrudes. Less than 18 grains and the loading lever stops before it seats the ball on the powder. To continue seating does place it too far down and out of the restricted area. I know this, because I deliberately did this, in the past, seeing what would be a minimal and max for my gun, volume wise.

If for some reason the ball is too loose, then the gases will escape around the ball.
then the ball either won't go down the barrel at all, or maybe only part way, or maybe go any distance.
Or if the ball is stuck and can't move. excessive pressure build up COULD cause the hammer to be pushed back off the nipple and the gas and pressure to escape back out the nipple.
Or the cylinder itself could burst.
In any event before you jump on me and say NO as in your reply.
Take into account I said MOST not all cylinders are bored this way.
Maybe I should of said MANY instead of MOST.
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