Author Topic: sprue up or out?  (Read 6855 times)

Offline yip

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sprue up or out?
« on: October 09, 2009, 12:20:15 AM »
  ok fellers its me again with a question bout the sprue on the ball. what gives the best accuracy sprue point'n up er down, or centered?its mighty hard to center the darn thingwhen loading. centing the thing seems best, does it matter?

Leatherbelly

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Re: sprue up or out?
« Reply #1 on: October 09, 2009, 12:48:55 AM »
 If your sprue is extruded, I'd load it up and centred. If it's tangental, I don't feel it matters. JMHO tho.( I aways try to find the tangent but it 's not as critical.)

Offline hanshi

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Re: sprue up or out?
« Reply #2 on: October 09, 2009, 01:47:53 AM »
I like the tangential sprue produced by the Lee molds.  I don't worry over them much but do try to find the sprue.  The ones with the standing sprue are carefully centered sprue up.  You can never be sure it's well centered if it's down because the sprue can't be seen. 
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Offline Roger Fisher

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Re: sprue up or out?
« Reply #3 on: October 09, 2009, 01:49:38 AM »
Up!

Daryl

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Re: sprue up or out?
« Reply #4 on: October 09, 2009, 04:05:04 AM »
Has to be up - down & you can't centre it every time.  The base of the ball'bullet is the most important, the top is very much less important in being perfect. 

Tangent cut sprues are less than the diameter of the ball, if measured (everyone I've done), and if that is sideways, there is a loose spot or weak spot on that side of the patch whether it's at a land or groove. This will cause that patch to burn, partically cut or whatever - I don't allow the possibility of my loading thus, to cause a missed target or poor hit on an inimal, so - it's spure up, with either standing spure of tangental cuttoff.

Offline b bogart

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Re: sprue up or out?
« Reply #5 on: October 09, 2009, 04:41:46 AM »
Up cause I was taught that!

Candle Snuffer

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Re: sprue up or out?
« Reply #6 on: October 09, 2009, 04:49:07 AM »
Up is the way I load them.  If memory serves, I believe the Bevel Brothers did a test with this very question.  If I recall they found very little difference in the performance - but I'm sure they took great care in loading the spur both up and down.

It's a whole lot easier to load it up then down.  May not always be perfect but it's sure easier to get it as close as possible to center from shot to shot.

sniper68

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Re: sprue up or out?
« Reply #7 on: October 09, 2009, 06:48:26 AM »
  OK fellers its me again with a question bout the sprue on the ball. Centering the thing seems best, does it matter?
Yes, should be spur up and centered. Although nitpicking, here is why.
Unless you follow a strict regiment when casting from a ladle and virtually all bottom pour furnaces will leave vacuum pockets in the balls. regardless of the size, the pocket will pretty much be above the horizontal center and perpendicular to the horizon. When these are present and you load with the spur up, they will be pretty much lined up center on the rotational center line and will have no effect on the accuracy, all else being equal. Below is an example of what I'm trying to explain....

Offline Artificer

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Re: sprue up or out?
« Reply #8 on: October 09, 2009, 09:55:05 AM »
Sniper 68,

Thanks for adding that photo and taking the time to split those balls.  Really demonstrates well your point.

Mike R

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Re: sprue up or out?
« Reply #9 on: October 09, 2009, 03:29:27 PM »
If it makes any difference, "up" was the way it was historically done, based on period writings from the early 19th cent.  The Bevel Bros, if I recall, did not find much difference in performance, but intuitively, up seems to make more sense.

Offline Dphariss

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Re: sprue up or out?
« Reply #10 on: October 09, 2009, 04:37:26 PM »
Its like Daryl said.
Sniper68, congratulations, very few people think to do something like this. ;)

Wondering just what variations in weight meant I once glued down a row of 380 gr 40 caliber BPCR bullets of different weights from the same batch of bullets and machined down through them .010" a a time.
I found no actual voids such as Sniper did. BUT I did find a difference in metal density along the centerline. In the bullets within 1 grain of nominal this was very uniform and as I machined down though this area of reduced density appeared and then disappeared uniformly. I.E. it got bigger as I cut down through the bullet to the centerline, then it got smaller as I cut deeper and then disappeared it matched the contour of the interior of the bullet pretty well but was fairly small, probably .05 wide at its widest point. It was well centered.
In bullets more than a grain light I found that the area of different density was NOT uniform. It would increase and decrease in size as I machined through the bullet and was off center at some points as well.
Lighter bullets tend to have air holes in them. Nice round bubbles at the base.
These bullets were all cast of an alloy made from lead and linotype (the bullet design required a hard bullet for accuracy), not pure lead. A ladle was used, this has proven to make the most uniform bullets for myself and other people who have cast a LOT of bullets over the years.
It is impossible to load match grade cast bullet ammunition if the bullets vary more than 1 gr +- and if things are going well it is possible to cull to +-.5 gr.
The bullets I check that were 2-3 grains OVER nominal, there are always a few, were SOLID no variation in the metal.
I believe that these differences in density and Sniper68s holes in RBs are the result of cooling and shrinking of the metal.
I weigh all cast bullets or balls for the above reasons using a digital scale, anything more than 1 grain "out" gets recast.

Slower twist rifle barrels, 48 or 72" etc are less effected by anomalies that a 16-18" twist slug or cartridge rifle. But it has to make a difference. But it may not be very apparent in limited testing. 1 or 2 10 round groups may very well be inconclusive just due to variations in the shooters performance at any given time.
I have no doubt that the cast ball is more accurate than the swaged ones, since none of these I ever checked were actually round. The cast ball generally is pretty round. I have no doubt that the weighed ball will out shoot the general run bullets, though a good mould and careful casting will produce a very uniform bullet/ball once the temperatures are all up and a uniform routine established. But there will still be variations and variables are what must be eliminated if shooting is to be its best.

Dan
He who dares not offend cannot be honest. Thomas Paine

sniper68

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Re: sprue up or out?
« Reply #11 on: October 09, 2009, 05:21:29 PM »
Voids occur because of out of sync cooling of the molten led. The lead "HAS" to cool in the proper sequence in the mold. You can easily see this when you know what to look for. First you have to pour and "KEEP the lead flowing. Lead shrinks when it solidifies. As you're pouring you you will see when, what I call the first set occurs. From the puddle on the spur plate you will see the molten lead be sucked in. That is the lead setting up around the bottom half and most of the outer perimeter of the mold. Keep going until the second set occurs, it will look just like the first. That will be the the rest of the lead except just around and under the spur plate solidifying. You now stop pouring. As you set your ladle down and pick up your wood spur plate hammer, or what ever you want to call it, the third set will occur, which the spur plate and the area just underneath. IF the lead on or around spur plate sets "BEFORE" you see the second(inner core set) you got a void, because if the inner core sets last, there is no molten lead to draw in as it shrinks. All this takes place in just a few seconds. Assuming all temps are correct, mould and lead, There ain't much to it, once ya get going......
« Last Edit: October 15, 2009, 02:24:13 AM by sniper68 »

Offline yip

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Re: sprue up or out?
« Reply #12 on: October 10, 2009, 12:22:27 AM »
    after reading all replys i got one or two questions  what the heck is a tangent? you say lee moulds sprue cutter does this. plus is a lee mould a good choise?

sniper68

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Re: sprue up or out?
« Reply #13 on: October 10, 2009, 12:53:36 AM »
Lee molds are fine, they are just a little more tempermental than steel when it comes to keeping them properly cleaned and lubed. They also heat and cool MUCH faster than steel molds and will require a slightly different pace to maintain proper temperature. once you get that figured out they work as well as any steel mold..

Daryl

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Re: sprue up or out?
« Reply #14 on: October 10, 2009, 04:16:17 AM »
No alluminum mould is as sturdy as a set of iron or evern brass blocks. A tangent cuttoff, is a slice off the surface of the ball, with no buildup protruding, as in Lyman moulds.

Levy

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Re: sprue up or out?
« Reply #15 on: October 12, 2009, 09:55:24 PM »
Recently, I unloaded a Type G tradegun barrel recovered from a local river.  It was loaded with a .55 cal. ball in a 24 ga. barrel (.58 cal) and the casting gate/sprue was up or toward the muzzle.  Occassionally, I get to unload a firearm that has been loaded for a very long time.

James Levy