Author Topic: sprues (Read 829 times)

maddmaxx · « **on:** June 11, 2004, 01:56:29 PM »

Something I can't figure: Why sprue up when loading? I can understand why not sideways, but why not down? Seems the flat would have less wind resistance if it was down. Nobody ever explained it. I probably didn't ask. If you take the time to explain, I'll be forever in your debt. Thanks. Maddmaxx

Thomas Krupinski · « **Reply #1 on:** June 11, 2004, 02:41:29 PM »

I'll take a stab at it Max, just a guess but I suspect that if the sprue is pointed down towards the powder the ball may turn as it is rammed down the bore leaving it to one side or another. There would also be a loose fit at the bottom between the patch and the ball. If it is pointed up, the ramrod squashes it as it is rammed.

Now I suspect that it really doesn't make much difference as the ball will squash under the pressure of the powder charge.

Anyone else have an idea or know the real reason?

New Hampshire · « **Reply #2 on:** June 11, 2004, 03:29:53 PM »

Ill just go by what Sam Fadala wrote in his Blackpowder Handbook. He says its a wierd mystery. He claims to have tested sprue up and sprue down. He says the sprue down opened up his patterns. Its wiered cuz you would think the opposite, as with the sprue down the ball is more aerodynamic.
Go figure.
Brian M.

filmokentucky · « **Reply #3 on:** June 11, 2004, 04:00:57 PM »

Maybe having the heaviest portion of the ball forward acts as a stabilising
factor?

jgalar · « **Reply #4 on:** June 11, 2004, 05:33:18 PM »

Two reasons that I can think of:
1 How do you know the sprue is actual dead center down, you can see it is dead center if it is up.
2 A sprue being down is similar to having a centerfire bullet with a bad base. The bullet will yaw after leaving the barrel instead of spinning on its axis. Even though you start out with a round ball after firing the bullet obturates to the bore and comes out a flattened ball or slight oval shape. You can probably imagine the variance in the flight of a yawing oval shape.

maddmaxx · « **Reply #5 on:** June 11, 2004, 06:27:17 PM »

well, thats some food for thought. It would be interesting to have some high-speed movies of a ball in flight. From a practical standpoint, I'm not a good enough shot to tell much from my own tests, but it's something that's always puzzled me. Thanks for the replies. I'm forever in your debt!

Gatofeo · « **Reply #6 on:** June 16, 2004, 06:12:32 AM »

The most common reason to have the sprue up is so you can visually affirm it is centered. If you place the sprue down, out of sight, the ball can easily slip to one side or another and the sprue won't be centered.
The need to center the sprue is controversial. Some claim that the little nubbin will affect the gyroscopic stability of the ball. Others claim it makes no difference. Test yourself and decide.
I place the sprue up, centered, out of habit. Been doing it that way for over 30 years. I'm too old, grumpy and set in my ways to have some whippersnapper tell me otherwise ... :evil: