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Sprue

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Twowithone

40 Cal.
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A friend told me on roundballs theres this mark or something I have trouble seeing it but its called a sprue and that sprue when loaded should be looking at you when you start to load your rifle supposed to help in accuracy supposedly. Thanks :thumbsup:
 
The sprue is the place where the lead was poured into the mould. I leaves a small mark, sort of like a pockmark on the ball. Swagged balls do not have a sprue. They are pressed into shape rather than moulded. The reason to put the spru in the front (or rear) is to prevent a spit-ball effect. The sprue woud upset the air flow over`the`ball, to the side, and cause the ball to "dance" or curve.
 
If you have trouble seeing it, it's a swaged ball. You will have no problem finding it on a cast ball.

Jim
Honestly I have shot the sprue in every position possible just out of curiosity, and could not tell a difference

Josh
 
Twowith;

The sprue is more easy to consistently load if you load it sprue up rather than sprue down, only because you can visually center it in the center of your bore. But regardless where you load it, it's not going to stay there when it flies. It is a physical impossibility to perfectly center the sprue and perfectly balanced balls is a physical impossibility as well. The sprue is going to rotate in ever-widening circles as it travels through the air. This is called wobble and eventually the sprue will find itself to the rear of the ball and then it's going to start over again until it finds itself back at the front of the ball (depending on time of flight of course. Hitting a target will end this wobble.)

You can test this by spinning a ball with a sprue on a table top. Start with it at the top and start with it at the bottom. You will see how it wobbles. Rifling helps overcome the negative effects of this wobble, but doesn't stop it from happening.

Dan
 
captaincaveman said:
If you have trouble seeing it, it's a swaged ball. You will have no problem finding it on a cast ball.

Jim
Honestly I have shot the sprue in every position possible just out of curiosity, and could not tell a difference

Josh
The Bevel Brothers ran spru position vs. accuracy tests (Muzzlelblasts Magazine) and they concluded there is no consistently measurable difference in accuracy based upon spru position.

I've shot a few hundred cheap and poorly cast balls with obvious ugly sprus out to 50yds, intentionally starting them without any concern with spru position to see what I could see, and never saw any difference either...I did not try 100yds but I'll take the Bevel Brothers word for it.
 
TWOWITHONE said:
A friend told me on roundballs theres this mark or something I have trouble seeing it but its called a sprue and that sprue when loaded should be looking at you when you start to load your rifle supposed to help in accuracy supposedly. Thanks :thumbsup:

[url] http://www.muzzleloadingforum.com/fusionbb/showtopic.php?tid/198505[/url]
[url] http://www.muzzleloadingforum.com/fusionbb/showtopic.php?tid/191546[/url]
[url] http://www.muzzleloadingforum.com/fusionbb/showtopic.php?tid/201385[/url]
[url] http://www.muzzleloadingforum.com/fusionbb/showtopic.php?tid/134140[/url]
 
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Dan, you may be right but in doing penetration tests, where the bullet is stopped by the medium that I was shooting into, I've always found the
sprue to be right on the front end, same place as when I loaded it. Not only from rifles but even from smoothbores. Maybe it's the distance, these tests would ,usually, be from 50 yds. or less.
 
Well, the amount of effect the wobble the sprue would impart on the ball would depend on velocity, rate of twist and distance to target as well as the actual size of the sprue and the weight it placed on surface of the ball. If you've nipped your sprues and pressed them down during the loading process with a short starter or such, their effect on the ball will be minimal. If they are as cast, give it a try on a table top. If you do it well, they will spin like a top for a period, before beginning their wobble. Given your twist rate is probably fairly slow, we could expect to see the wobble begin some distance from the bore. With a smooth bore, there would be no wobble. I'm not a strong math student.

Dan
 
Dan, the ball is spinning a heckuva lot faster from a barrel than we can spin it on a table, and thus is a lot more stable in flight. It's unlikely that the wobble would even begin to show up at the distances that PRB are shot. The sprue will always be off center, as you said, and that will always cause vibration in flight. Probably one of the reasons that swaged balls are considered to be more accurate. I'm not a competition grade shooter and I don't normally notice a lot of difference between cast or swaged though.
 
holt on there twowithone,

thought your luck would hold out forever dija?? well it didn't, here i am... :blah:


some of these old hard and fast rules of thumb are just that, old, old, rules. 'sprue up', is one such rule.

don't know how old you are, but, back in the old days a bullet mold was a tong tool. it cast one ball at a time, when the mold was open, the ball fell out WITH the sprue attached. the tong had a built in sprue snipper in the handles. you held up the ball and sprue and snipped that rascal off :) now what you had was a ball with a significant sprue. THAT sprue had to be put straight up as it had some weight to it..

if they had molds in the days of yore ( ml talk for a long time ago ) LIKE WE HAVE TODAY, THAT TRIM THE SPRUE WHEN THE MOLD IS OPENED WITH NO TRACE OF THE SPRUE, oops, cap lock was on :redface: i doubt we would ever, ever, have heard the expression,'SPRUES UP'

remember the above was just a grampaisum.. :grin:

..ttfn..grampa..
 
Plink;

You're absolutely right...kind of. But it doesn't matter because what you're absolutely right about is the most important part of the equation. The effect wobble has on the ball is overcome by the spin, but the wobble doesn't disappear. If the sprue isn't absolutely perfectly placed, it is going to manifest wobble from the very start of its rotation. But, it's that very rotation that overcomes the effects of wobble. Like the "Archer's Paradox" you have a "rifleman's paradox as well." Rifling helps overcome bullet instability because it is a given that human manufactured (and placed while loading) bullets will be inherently unstable without it. Watch a child's top. At the point where its spin is the greatest, it is most stable. As the spin decreases, issues in balance manifest themselves in wobble.

But again, none of this matters much because the ranges we shoot our round projectiles are too short for the wobble to adversely effect accuracy. The long range shooters experience a different set of variables.

I find it fascinating that our heritage as riflemen was born with such primitive - yet incredibly effective tools. A mountain man sitting around a campfire molding balls and cutting patches might not have known what he was doing wasn't perfect. The elk didn't know it either!

Regards;

Dan
 
Alls I know is I shoot cast balls with the sprue up for plinkin, and hornady .495 swaged balls fer serious competition! :rotf: Really!
 
I do the same, use swaged balls for competition
but not because they are more accurate but just so I don't have to worry about where the sprue is.
 
some times when casting you also get an incusion or air pocket at the sprue by centering it you will keep this lighter part of the ball at the top centered to lesson the " woble". My 2 cent Fisher King. :v
 
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