Just Another Mystery

[nkbj]

Molded up some 451's to find out if they worked better than 454's. Just went out back to see.
I pulled the first shot to the left. The last two shots felt like they had far less power, less smoke and sparks. And look how much less penetration there was.
I went back to the bench and checked the powder measure; still set firmly on 30 grains.
Oh well. It's always something!
http://i791.photobucket.com/albums/yy192/SNARGLEFLERK/451RB30GRFFFgTARGET.jpg

 

[R.M.]

Just out of curiosity, what is the groove diameter, compared to the chamber diameter?
If the chamber is cutting the ball smaller than the groove diameter, hot gas can be blowing by the ball while it's in the barrel. This will cause leading in centerfire guns. Never seen it in a C&B, but who knows.

 

[nkbj]

Haven't miked this one but you can just see light through the groves around the .451 ball. So, reckon the grooves are bigger than the chambers.

 

[F.G. Ford]

Hey Goodcheer,
Something is not right.
That Navy should bury those balls.
Is that tree stump pine? If it were Ironwood, that woud be another story.
I believe .451 balls should be too loose.
My Dragoon uses .454 balls.
Soft lead balls should compress well, and expand well on powder ignition.
Also with the larger balls your group should be more consistant.
Best regards.
Old Ford

 

[nkbj]

Well you know, they make the grooves larger of a purpose, that having been the 1800's accepted practices of how to make a barrel for soft lead and black powder.
And, the lands displace lead that moves to the grooves to some extent as well as the pressure squishing it from behind.
But...it sure does seem that the chamber mouths really oughta be just a leetle bit bigger don't it?

 

[mykeal]

Just out of curiosity, what is the groove diameter, compared to the chamber diameter?
If the chamber is cutting the ball smaller than the groove diameter, hot gas can be blowing by the ball while it's in the barrel. This will cause leading in centerfire guns. Never seen it in a C&B, but who knows.

It's very common in cap and ball revolvers. Many of mine have that flaw to one degree or another. Someday I'll shoot well enough to fix it.

 

[CoyoteJoe]

I'm wondering why you went to a .451" ball in the first place. As a rule of thumb, the largest ball you can load is generally the best for accuracy, reliability and safety. I'm thinking perhaps your last two shots were weak because the ball did not fit the chamber tightly enough and recoil of the previous shots had moved the ball slightly off the powder.
When I unwrap a new revolver the first thing I do is measure the chamber throats. I want a throat diameter at least equal to the groove diameter of the bore. Perhaps .001" over groove diameter. That holds true to cap&ball as well as cartridge revolvers. The groove diameter of C&B revolvers does seem pretty consistent at about .451"-.452". Chambers however, are never consistent, most running well undersize. I recently worked on a '58 Remington with chambers of only .442". A ball, after ramming into a chamber would literally fall through the barrel.
Since pure lead has very little rebound an oversize ball will come out at chamber diameter no matter how large it measured before loading.
I hand ream my chambers to .452" and use a ball of at least .454" or .457" is even better. I also lightly bevel the chamber mouths so that seating a ball does not cut the fall to fit but swages it to fit. That will better center the ball and provide a tighter fit than a cut ball.

 

[nkbj]

The balls were well swaged into the chambers and seated firmly. It's just one big mystery. And, I haven't had day time enough to spare to go play some more and figure it out.
The reason for going to .451's is how hard I have to get down on that skimpy loading lever with .454's. Was trying to get more consistent loading. But, the .454's may end up being better.
That Remington of yours with the .442 chambers, how did it shoot after you opened it up?