Bullet Casting

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  • Last Post 28 June 2011
xgrunt posted this 02 December 2008

I have just cast some 180 grain .357 bullets, for use in Field Pistol/Metallic Silhouette matches.  The mould is a gas check double cavity mould (base pour) by RCBS and I'm using a mix of 50/50 lead and linotype.  I find that on a number of the bullets, I have a bit too much sprue on the bases, probably caused by the sprue plate being too loose.

Bearing in mind that these pills will be covered by (Hornady) gas checks, does anyone out there know whether or not the excess sprue will adversely affect accuracy?

And if so, if I (carefully!) level the sprue off the bullet bases, would that solve, or partially solve the problem?

I really don't want to chuck the bullets back in the pot and start again - I'm too old and grumpy to enjoy doing any more casting than I have to!

I'd appreciate any feedback.

 

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cityboy posted this 02 December 2008

I would say you have a problem. When I get a rough sprue cut I cut the lump down using a flat file. Best results are obtained if the bullet is held in a small V-block during filing. This keeps the base square with the axis of the bullet.

Cityboy

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RicinYakima posted this 02 December 2008

Ex-Grunt,

You only have a problem if, during seating the gas-check and sizing, the base isn't square with the sides of the bullets when you're done. My revolver alloy is alot softer than yours (WW's + 2% tin), so it swages down flat when seating gas-checks.

Ric

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CB posted this 03 December 2008

I doubt if you'll have too much trouble but you might want to think about getting a set of welders gloves and cutting the sprue by hand. That way you can put a little downward pressure on the plate. When I get a bullet that has a bump on the bottom I just slide the plate back in position and cut it off again.

Only way to really tell is to shoot a few and see how they are.

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gunarea posted this 03 December 2008

Fellow Xgrunt

   The more you mess around with the slug, the more apt you are to introduce inconsistencies. There is no soft answer.  Adjust the sprue plate.

                                                                                               Roy

Shoot often, Shoot well

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JetMech posted this 03 December 2008

There's another thread on this: subject:http://www.castbulletassoc.org/view_topic.php?id=2421&forum_id=63.>http://www.castbulletassoc.org/viewtopic.php?id=2421&forumid=63. I've had the same issue with some Lyman 311284s some years ago. At that time, I tried the filing in a V block and found it a PITA, with the file teeth filling up, along with worrying about changing the base alittle as gunarea pointed out.  You could segregate the bullets and see if there's a difference in accuracy and point of impact. From the thread referenced, you may find there's no difference, but I would think there would be as the bullets with the bump should be heavier.

Ed Harris has a method I thought about back then: setting up a jig to hold the bullet and trimming the base in a case trimmer. I just don't have the equipment to make a good holder, but the results should be consistant.

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mugs posted this 03 December 2008

Get some BullPlate lube for the top of the blocks and the sprue plate. Use gloves and cut sprues as soon as they're solid. Cures all bad bullet bases.

Mugs

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Dale53 posted this 14 December 2008

I've been cutting sprues by hand for a number of years. It works wonderfully well for up to four cavity moulds. My Lee six cavity moulds have the sprue cutter handle that essentially does the same thing with the advantage of a cam to do the work.

My bases are much better since I have been doing things this way.

Dale53

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CB posted this 14 December 2008

I also cut my sprues by hand on all of my molds except for the big heavy steel multi cavity Lyman and H&G molds.

I use Veral's sprue plate lube beeswax/graphite very sparingly. I havent had a sprue bump in several years.

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TRKakaCatWhisperer posted this 16 December 2008

I use a high temp silicone grease and mix in (used to use MDS or graphite) a little titanium dioxide for lubing the sprue plate - handles the heat well.

 

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dardascastbullets posted this 17 December 2008

xgrunt wrote: I have just cast some 180 grain .357 bullets, for use in Field Pistol/Metallic Silhouette matches.  The mould is a gas check double cavity mould (base pour) by RCBS and I'm using a mix of 50/50 lead and linotype.  I find that on a number of the bullets, I have a bit too much sprue on the bases, probably caused by the sprue plate being too loose.

Bearing in mind that these pills will be covered by (Hornady) gas checks, does anyone out there know whether or not the excess sprue will adversely affect accuracy?

And if so, if I (carefully!) level the sprue off the bullet bases, would that solve, or partially solve the problem?

I really don't want to chuck the bullets back in the pot and start again - I'm too old and grumpy to enjoy doing any more casting than I have to!

I'd appreciate any feedback.

  The raised portion of the sprue on the bases will indeed affect accuracy. The sprue should be cut clean without a divit or raised area. The area should be smooth and shiny. The base is the most important region of the bullet. Destroy the integrity of the base and the accuracy potential of the bullet is destroyed. You may want to consider remelting the bullets and casting some high quality cast bullets or face an unpleasant time at the range.

Matt

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CB posted this 18 December 2008

Again one must make sure the sprue plate is adjusted properly and lubed sparingly. If you are smacking a 2 cavity with a mallet then you are striking with too much downward pressure. There are guys that offer aftermarket replacement sprue plates that are thicker and are of a different design so you can break them by hand. That will fix your sprue bumps.

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JetMech posted this 18 December 2008

One thing I learned here was that the sprue plate has to be adjusted to open freely when the mold is HOT. That fixed most of my problems. I'm also getting some Bull plate lube to help.

If you are using Lyman molds, the replacement sprue plates you can purchase are an upgrade to a thicker material and they are less expensive than the custom plates available.

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raytear posted this 26 June 2011

Some random thoughts on casting/things I have discovered.

Along with properly adjusting sprue plates, if I am having trouble getting the corners of the bases to fill out to a sharp edge rather than rounded contour, sometimes it helps to use just a little less pressure when holding the ladle's spout against the sprue plate as the metal flows into the mould.

With some moulds and alloys, when cutting the sprue, I get a cleaner cut if I strike the plate at an angle that not only cuts the sprue, but also VERY SLIGHTLY forces the sprue plate against the top of the mould. Too much of this I would imagine could eventually bend the sprue plate, so I use great caution.

If I have a sprue that sticks to the plate, it sometimes helps to swing the plate back on top of the bullet, then tap the top of the plate a couple of times. Take care not to bend the plate as mentioned above.

With some moulds and handles, I get better results if I mount the blocks backwards. That is, if I have to strike the sprue plate in a direction that forces the mould back towards the handles, rather than in a direction that wants to pull the metal stubs out of the wooden grips.  I have one previously owned mould where the haves do not line up properly when mounted conventionally, but come together perfectly when mounted “backwards".  (The original owner warned me about the misalignment.)

The lead alloy ends of battery cables may be kind of dirty when old and ready to be discarded. However, I have found that, when cleaned up and added to particular batches of metal, they can greatly improve mould fill-out.

Old candle stubs cut into rounds like coins make great pre-measured doses of flux.

A propane torch is handy when casting. I have one with the push button control that starts the gas and trips the piezo electric lighter.  Works great for lighting the Coleman camp stove I use or melting, and for lighting off the flux.  I use the pencil-flame tip.

My gas heated lead pot gets up to casting temp much faster if I put the lid from an old sauce pan on top of it to hold the heat in. 

I have both Lyman and Lee lead pots, but find a stainless steel dish about 2.5” deep and about 5 or 6 inches across works well and holds more metal.  The wider flat bottom is more stable on my Coleman stove's grate, too.

Good shooting! RT

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LWesthoff posted this 26 June 2011

On single cavity molds, and on SOME (not all) of my double cavity molds, I can cut the sprue by hand. With a reasonably well adjusted sprue plate, this gives me a very nice flat cut-off. One thing that helps greatly is that I wear regulation Firemen's Gloves. They keep the heat out much better than welders gloves. I buy 'em mail order; there are several sources that advertise on line. I shoot Production Rifle and Issue Military rifle class, so all of my bullets are reasonably hard (lino or 2-7-91 alloy, NOT heat treated) and they all wear gas checks. I have not found that small sprue bumps that show even through a properly installed gas check have a detrimental effect on accuracy out to 300 yards, AS LONG AS THEY ARE REASONABLY CENTERED ON THE BULLET BASE.

Your mileage may vary, but this works for me.

Wes

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CB posted this 26 June 2011

mugs wrote: Get some BullPlate lube for the top of the blocks and the sprue plate. Use gloves and cut sprues as soon as they're solid. Cures all bad bullet bases.

Mugs I tried to like Bullplate, but just don't see an appreciable benefit to it. I let my sprues set up firmly, and never seem to see any smearing. I do break sprues by hand, and have for many years.

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RicinYakima posted this 26 June 2011

Raytear, you are really digging up some old posts! I didn't know anybody looked back that far.

I use the same technique as Wes, and think it works as well as anything else, and is fast, especially if you are ladle casting. And like WEs, I can't find any difference if the lump or pit is centered in the base.

Ric

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CB posted this 26 June 2011

RicinYakima wrote: Raytear, you are really digging up some old posts! I didn't know anybody looked back that far.

I use the same technique as Wes, and think it works as well as anything else, and is fast, especially if you are ladle casting. And like WEs, I can't find any difference if the lump or pit is centered in the base.

Ric Holy smoke! I missed that completely!

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raytear posted this 27 June 2011

RE: digging up old posts

Well, it was a matter of finding a topic that was similar as I did not want to start a new thread.

I have trouble getting gloves that fit right.  I have VERY wide thumbs; what some folks call Swedish thumbs. By the time the thumb is wide enough, the fingers are too long, so hand cutting sprues is something of a non-starter for me. 

My experience with cutting sprues as soon as they are set up is that I get tear-out in the center of the base.  I need to let mine cool a bit more than that.  Of course, striking the sprue plate with a mallet is a more abrupt action than shearing by hand.   .44 & .45 caliber bullets seem to be the worst offenders for me. However, that does suggest a project for making a tool that will slip on and off the tab of the sprue plate so I could operate it by hand.

Good shooting! RT

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RicinYakima posted this 28 June 2011

RT, I have several moulds with threaded holes for a handle attachment for the spue plate. I've never seen a modern one, but old timers who cast without gloves added a handle to operate the plate. There isn't anyting new.

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CB posted this 28 June 2011

Buy Veral (LBT) Smiths book. In it, he details modifying sprue plates to allow the use of a tool to break the sprue. It's pretty simple, and every caster should have the book anyway. He's a sponsor here, and a link to his site is on the masthead somewhere.

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