Lyman 311041 Woes!

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I spent a couple of hours casting with my Lyman 311041 today. Two hours wasted! Every single one came out under-size. Man do I hate this mould!! I'm running 94-3-3 alloy. This mold will only work with a melt temp of 640-660. Any hotter and lead will run into the vents. If I pace myself correctly and keep the mould in the "sweet spot" (heat-wise) it will drop good boolits at .310-.311". Perfect size for my Marlin 30-30's Microgroove barrel. Too much heat, they come in under-size, too little and it's wrinkle city. It's a very, very narrow operating range. Anyone have any ideas??

[MT Chambers]

Are you preheating the mold on a hot plate?

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Yes, the mould is preheated. The first 3-4 casts show a wrinkle on the nose, always in the same place. After that, if my cadence is correct, I'll get good boolits. If not, they're either wrinkled or undersisize, depending on mold temp. I've never had a mould so unforgiving in this respect! Very frustrating!

[OS OK]

When casting, are you sitting so that you can see the Pb stream going directly into the hole in the sprue plate?
If you are running the stream into the sprue like a funnel the sprue will rob that first part of the stream just enough to put light wrinkles in the nose and up the side of the nose...whooda thunk?
I have a 311299 that will do the same thing, believe me I wrestled the pot and mould temps. with that one.
Finally I built a platform to raise the pot so I can see the stream...temps are still a priority but other than that...problem solved.

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No, I'm pressure pouring with a ladle. I haven't tried just pouring into the hole, might have to bump the pot temp up but it's worth a shot. Might be able to avoid the lead flow into the vents and improve the wrinkled nose situation.

[runfiverun]

the pressure is forcing the alloy into the vent lines.
the extra tin makes it possible.

[OS OK]

I don't know what the mating surfaces between your mould looks like but...cleaning it as best as you can and checking that the mating pins and slots are clean.
It doesn't take too very much to hold the mould open enough to get finning. Hold it up to the light with the sprue plate open and out of the way and sight between the mating halves of the mold...see if you can see light coming through the crack in between the mould halves. It should shut tight and keep light from coming through.

I had this happen with a little 2 cav. Lee I bought used. The guy used to smoke the mould very heavy...after I cleaned it as best as I could...it stopped finning.

[popper]

Way too much tin.

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The mould blocks mate tightly, no light shows between then, It doesn't fin, it lets the alloy flow into the vent lines, forming little whiskers or spikes. I had forgotten that tin is a wetting agent, when I made this alloy up I should have cut back on the tin. I'm thinking linotype and pure lead 1:3, that would yield 96-3-1 alloy. That's enough antimony to water drop with good results and less tin should reduce the "flow" problem, yes?

I tried some pouring experiments again yesterday. Best results were pouring into the front cavity only (not pressure pouring), treating it as a single cavity mold. No great success but it did reduce the number of rejects significantly. Really slooowwww going, ugh!

[kungfustyle]

try ladle casting. Get the pot up to about 750 and ladle cast. Works like a dream for me on my difficult molds.

[longbow]

I have an old Lyman 31141 that casts perfectly at 0.310"/0.311" with wheelweights. I wish new Lyman moulds cast oversize with wheelweights but that is a whole other topic.

I ladle cast but not with a Lyman dipper, I use an open ladle. I use a fairly large plumber's ladle that holds a pound or so of lead. I always find I get better casting when I pour through the sprue hole with a bit of a swirl in the lead by pouring a bit tangentially. I tried the closed Lyman style ladles but didn't like them so went with an open ladle (for about the last 40 years).

You might try loosening your sprue plate so that it swings almost freely. I find that if the sprue plate is too tight on some of my moulds casting is not as good as with a slightly loose sprue plate. I think the bit of venting that goes on under the sprue plate is a benefit.

On that note. I also have some moulds that fit so tight together that I put a very slight bevel along the top edges under the sprue plate to allow venting as the loose sprue plate wasn't enough. That has cured some problem moulds for me. I am talking a very small bevel put on with a diamond hone... a few thou only.

I'd try pouring the lead from the ladle to the sprue hole rather than the pressure casting you are doing. If the mould is very tight then it may not be venting as fast as you are trying to put lead in. With an open sprue hole air can escape.

I'd also try loosening the sprue plate until it just swings free to see if that helps. If so then that indicates there is not enough venting. You can then decide if you want to bevel the top edge of the mould or run a loose(ish) sprue plate.

Temperature is another variable but I don't use a thermometer so can't give numbers. I cast based on the colour of the lead and like to cast hot enough to result in slightly frosted boolits.

That's what has worked for me anyway.

Longbow

[Geezer in NH]

Duh! Read #5

No, I'm pressure pouring with a ladle. I haven't tried just pouring into the hole, might have to bump the pot temp up but it's worth a shot. Might be able to avoid the lead flow into the vents and improve the wrinkled nose situation.

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Sprue plates, yes I am a bit OCD about that! I deburr the bottom and edges of the plate and then adjust tension so it swings freely, of it's own weight. Over the years I've found this works best for me. I'm going to mix up some 96-3-1 alloy today and see what I can do with it. Perhaps too much tin has been the problem all along. We'll see!

[Dusty Bannister]

If the venting lines in the mold are too deep, this can allow whiskers to form on the casting. Have you tried rubbing a graphite pencil across the vent lines close to the cavity, on one mold block only? That short bullet should not have a lot of difficulty venting. Try this with the alloy you have in the pot, and then when you reduce the amount of tin, it might not need to have the vent lines partly blocked.

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If the venting lines in the mold are too deep, this can allow whiskers to form on the casting. Have you tried rubbing a graphite pencil across the vent lines close to the cavity, on one mold block only? That short bullet should not have a lot of difficulty venting. Try this with the alloy you have in the pot, and then when you reduce the amount of tin, it might not need to have the vent lines partly blocked.

I had thought of doing something like this but wasn't sure what to use. I'll try this before I switch alloys. It'd be nice if this works, I won't have to mess with another alloy!

[Wayne Smith]

First try just pouring into the mold without pressure casting. I only have one mold that demands pressure casting, my Lyman 457125. Pick up your temp to 680-700 and cast away. I'll bet you get good boolits.

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First try just pouring into the mold without pressure casting. I only have one mold that demands pressure casting, my Lyman 457125. Pick up your temp to 680-700 and cast away. I'll bet you get good boolits.

I have tried that method, Wayne, with mixed results as noted in post #9. However, I did not change the temp up from 650. I'll try that tomorrow. Today I tried the "pencil trick" as Dusty suggested and that was very successful in preventing the vent line problem. I'm still plagued with the undersized boolit problem that comes and goes. Mostly comes. My reject rate is awful. I've taken to casting 80 or so and then measuring each one. Culls go back in the pot. Needless to say, the pot is well fed! I mixed up some 96-3-1 alloy before I called it quits today, we'll see what happens tomorrow. Thank you all for your suggestions, I'm hopeful we can work this out!

[Larry Gibson]

Before calling it quits empty the pot out and and try another alloy. Sometimes a mix can get contaminated or is not what we think it is. You might also try a Lyman or RCBS ladle using the method Lyman shows in numerous of it's manuals. I have cast thousands of bullets with Lyman dippers/ladles w/o any problems. A lot of those were with various Lyman 311041 moulds.

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Larry, yes, I have both Lyman and RCBS ladles, I much prefer the RCBS! I do not have a Lyman manual, could you please describe this pouring method you speak of? Yes, a different alloy, as I mentioned above I have mixed a batch of 96-3-1 to see if less tin might be beneficial. I have been casting with 94-3-3 for several years now with nary a worry. It has produced great bullets in all my other moulds, but not this one! I am sure the problem is mould temp; if I can just nail that down....... It's irritating that at times I can go along and cast good bullets of .310-.311" OD and at other times they are comingout at .308-.309". I think this mould is cursed!

[OS OK]

I've posted this chart any number of times when the actual Pb blend is in question, perhaps you have seen it before or not...but, the same mould will give significantly varying results in size and weight when different Pb blends are used...sometimes what we have in our stash is a little different and we are unnaware till a problem like this comes up...

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Hope this helps to shed some light...