What in the world? Lee RB dropping far too small

[deerslayer303]

I was running out of .490 RB for my smoke poles, so I got out an old Lee 1 cavity and whipped out a hundred or so. I never thought to measure them as I always just shoot muzzle loader projectiles as cast never a problem until now. So today I got out the boom stick and struck out to the back yard. Umm when I layed one of these on top of a patch I almost didn't need a ram rod. I slid it down the barrel anyway and fired one off. Yeah nowhere near the target, actually about 4 feet over it. So I got to looking and yeah, no wonder. In the pic, the RB in question is in the middle. A Speer store bought .490 on the left and a hand cast .454 on the right. The batteries are dead in my caliper, so I can't measure it. But I don't need it to see its too small. I've never had them drop so small before.

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[deerslayer303]

I went and got my Dad's dial caliper and it looks like they are measuring right at .470 ish. Give or take.

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[Beagle333]

and you're casting them out of pure lead? And not at some really high temp, like 900°?

[deerslayer303]

You know, now that you mention it. I forgot what's in the pot. I know I cast up some 158 SWC a little while ago. Hmm. Well I'll go out here and fire up the pot and empty it and put known pure pb in it and try again. I'll throw this lead in the unknown bucket until I can test it. I had my Lee 10lb Pot on 7 where I normally cast. That was the first time I've used that old 1 cavity Lee mold. I will get out the newer 2 cavity and cast a ball with both to compare.

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[Beagle333]

Regular bullet mix should cast bigger than pure lead anyway. The only thing I can think of would be excess temp, but even then I don't know if you can get that small with just heat.

[deerslayer303]

I just got done recasting some more. The results are the same. The 2 cavity Lee drops em about .491ish (if I'm reading this old caliper right) the 1 cavity mold still .470's. I think this mold is just simply the wrong size. Weird, I've never heard of that before with the Lee molds. It is an old one. That's ok though, a good friend of mine can fix it pretty quick.

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[m&p45acp10+1]

Hot mold. In fact it should be so hot when you use some synthetic 2 cycle oil for lube it should smoke like a coal train. Get the alloy to at least 800 if pure lead. Also give them an extra three seconds in the mold after you think you need to drop them. I do not cast them, though I have a friend at work I helped out with the same problem. Also a tiny touch of tin can help. Also flux twice. Then wait a minute, and flux again. Do not use wax flux use some media from a tumbler, or saw dust. Use a match to keep it from smoking so bad.


Oh and degrease the mold to make sure that is not the problem as well. I use brake parts cleaner on mine, and on the one that was such a problem for my friend.