Casting problem

Discussion on Bullets and Bullet Lubes, Casting, Swaging, Paper Patching, and Lube Cookies.
PostsCOLON 18
JoinedCOLON Tue Dec 19, 2006 3:58 pm

Casting problem

Post by Throck3 » Tue Apr 03, 2007 7:33 am

I was casting this weekend and ran up against a problem. I am fairly new to all this and am learning from doing...and listening from you! Hopefully, you can give some advice on this.
I was casting a batch of Lyman 535 grain Postells for .45-70. I was using 20-1 alloy heated to about 730 degrees in a Waage furnace. I dump my bullets onto a folded towel. I have cast around 500 of them now and usually cast about 120 in a batch (to allow me to cull out some that weigh too light or too heavy and still have a 100 usable closely weighted bullets). I have had other problems using this mold but they generally cleared up after buying some good alloy from J. Walters. This time, after cooling 4-5 hours, I started weighing and segregating the bullets. I usually line them up on pieces of lined paper and segregate them by tenths of a grain of weight. I started to notice that some of the bullets were very wobbly when set on their base. On closer inspection, I noticed the base was very warped on many of them. It appears that the base of the bullet warped downward from the line formed by the bottom lube cannelure. In fact, on the side that has bent downward, there is a slight, but visible cracking along the interior line at the bottom of the cannelure. I normally have to tap the handle brace that holds the mold to get the bullet to drop out, but don't think that this would cause the bottom cannelure to bend down. I am not sure when the warping occured, whether at the time they left the mold or after they coooled. Anyway, I will have to remelt and recast this whole batch because of the warped bases.
Any thoughts as to the cause of this occurence and a fix?

North TX

ND Sharpshooter
PostsCOLON 34
JoinedCOLON Sat Dec 10, 2005 3:37 pm
LocationCOLON Devils Lake, ND

Post by ND Sharpshooter » Tue Apr 03, 2007 7:45 am

In my experience incomplete fillout usually occurs when either or both the melt or the mould are too cool. Another option is that your rate of fill is too slow. If the mould is free of contamination try increasing the temp or flow and see what results you get. Are the mould's vent lines clean? Just some thought looking back on when I first started moulding cb's. Good luck.
"Never said I didn't know how to use one."

PostsCOLON 115
JoinedCOLON Fri Dec 09, 2005 2:34 pm

Post by powderburner » Tue Apr 03, 2007 8:24 am

if the base band was torn and the base tipped you have not let the mould cool enough before opening it , and are pulling the bullets apart .
With the Lyman mould if you tap the handle pivot screw a couple times BEFORE opening the mould the bullets should release a whole lot easier...
after the spru hardens and changes color wait 5 seconds and then cut the spru then wait maybe 10 sec to let the bullet harden ... then release it from the mould. these numbers are just for example

there is a good article on casting at that uses a clock type casting cycle... ................Dean
Dean Becker
Myweigh scale merchant
lover of 74 sharps
NRA lifer

PostsCOLON 18
JoinedCOLON Tue Dec 19, 2006 3:58 pm

Post by Throck3 » Tue Apr 03, 2007 10:00 am

Thanks. I forgot to mention that I was getting a full cast bullet, so I don't think that temperature of the alloy was the problem. I also had the mold quite hot before I started casting. I cast a few to see the quality of the bullets before I started keeping them.

I was leaning toward the problem being the mold being so hot and the bullet not quite set completely before I open it up. The bottoms of the bullets just look bent and the lower cannelure creases appear to be torn. I will read the supplied link about casting by time count. That may very well be the problem as I had the mold sitting on top of the furnace as it heated up. The alloy rose to the level of the mold as it melted and the mold was sitting about a half inch into the alloy for a while before I started to cast. It was very hot and I actually only had a couple of bullets with signs of being too cool before I started getting what I thought were decent bullets.

Thanks again.

User avatar
Ranch 13
PostsCOLON 1584
JoinedCOLON Mon Nov 21, 2005 9:41 am
LocationCOLON Eastern Wy

Post by Ranch 13 » Tue Apr 03, 2007 1:02 pm

If the screw on the sprue plate is to loose or tight can cause some problems.
Might be you were dropping to soon, and dinging the bases as they hit.
To add a bit to Powderburners suggestions I have an old catalog, under a peice of carpet padding, under an old handtowel that the bullets drop from the mold onto.
With the big 45 bullets I give them the roll test before I weigh them, if they won't roll a relatively straight line and do it smoothly, I don't even weigh them, just pitch them back because they have either warped, or have an airbubble someplace.

PostsCOLON 97
JoinedCOLON Fri Nov 25, 2005 3:36 pm
LocationCOLON Roughrider country

Post by Ironramrod » Tue Apr 03, 2007 3:10 pm


I've run into the same bent bases on the bigger bullets from Lyman moulds (#457132 and #457125). The way I solved the problem was to swing the sprue plate around during the cut-off procedure about 180 deg. from where it is when filling the mould. Then, while opening the mould slowly push down on the sprue plate top with a block of wood in your other hand. The mould then opens right up and the bullets don't have a bent base.

That seems to cure the problem for me, but I really think the problem is that Lyman has the mould handle grooves cut in the wrong place for those bullet designs; the mould halves tend to hang up on the bearing bands but not the nose, causing the mould to tend to open at an angle and often bending the bases. I would like to see Lyman move the handle grooves somewhat toward the bullet base, and I think that may solve the problem. I have sent Lyman a couple of e-mails re: this subject in the past, and have never heard anything back.


Highwall Jack

Post by Highwall Jack » Tue Apr 03, 2007 3:53 pm


Sounds like mold too hot as others have said.

The way I manage mold temperature is to time how long it takes the sprue puddle to change states and try to keep this consistent by cooling the mold in front of a small fan (the one blowing the pot fumes away from me) for a specific amount of time after the sprue puddle "sets".. Usually this is a few seconds more than the sprue setting time.


Kelley O. Roos
PostsCOLON 944
JoinedCOLON Sun Nov 20, 2005 6:55 pm

Post by Kelley O. Roos » Tue Apr 03, 2007 5:26 pm

What is happening, the nose section of the mould is opening slightly first, and the base section of the mould is still closed causing the bullet base to rise and the crack or tear in the lube canal next to the bullets base. Hold the same tension across the moulds side so the mould will open evenly. The mallet your using to tap on the handle hinge will work for a tensioner, hold mallet against the nose portion of the mould will slowly opening the mould evenly.

Kelley O.

PostsCOLON 18
JoinedCOLON Tue Dec 19, 2006 3:58 pm

Post by Throck3 » Tue Apr 03, 2007 8:31 pm

Thanks one and all. I appreciate the sharing of knowledge here. I am learning a lot from you all. I hope to meet some of you at the silhouette matches soon. Maybe Mexia or Graham, TX.