Old Mag 20 - frosted bullets or spout freeze...

[lurch]

Folks,

I have an old Mag 20 pot that I got used, cleaned up and started using. It melts lead just fine and will run plenty hot - over 800F according to the thermometer. I have 2 molds though that give me absolute fits with it though when trying to bottom pour. One is a single cavity 429215, the other is a dual 358495. Both molds want the metal (WW w/2% Sn) to be in the 600F or so range to get good fill out and not have problems with frosted, rounded off corners on the bands.

Unfortunately, running the pot at this temperature results in a lot of spout freeze ups. I keep a propane torch handy to get it going again - as did the previous owner apparently since the paint was burnt around the spout when I got it. Is this typical with these pots? If I run the melt hotter all I get are frosted shrunk back band edges on one side or the other of the bullet (at least that's what I think is happening - metal cools and pulls back out of the corners). I have tried using a little bit of the damp rag (bump the bottom of the mold on the rag every now & then) treatment but that is not working - or rather I have not got it figured out. I get to the point where I get wrinkled noses before it does much of anything to help the frosted bands in the middle. I'm guessing here, but I think the cast rate I have tried to slow down to is on the order of once every 30 to 45 seconds at a temperature where the spout won't freeze up - still get the frosted corners.

Other molds seem to work OK.......couple of 45's & another 38.

I can ladle cast them reasonably well at a higher temperature melt but am not too thrilled with ladle casting - just not my personal preference for how to do it. Makes a big mess for me with little drips & spatters of lead all over the place. Though if it comes down to it, I'll get over it.

Anybody have any ideas on what to try to get the bottom pour happening?


BTW - as part of the cleanup, I had to take the housing off to re-wire the indicator light. The factory assembly had routed the light wires too close to the pot and the insulation had long since burned away leaving the wire free to corrode and break (glad it hadn't shifted and gotten that bare wire up against the housing - a lead pot with teeth...:roll: ) Noticed that the "spout" must be 3" or so long. Seems to me like that's asking it to freeze up....

[GP100man]

lurch

welcome to the forum!
seems like new members are getting closer & closer!
if i could get the covers off id put me some more insulation
around everything!!

ps ive eaten lunch in meadows many times!!

GP

:castmine:

[Dale53]

Lurch;
I have been casting bullets for longer than I care to comtemplate (over 50 years and tens, if not hundreds, of thousands of bullets). I am still learning...

One thing that I HAVE learned is that each mould is a law unto itself. I am a bottom pour guy. I have learned to cast match quality bullets from 45 gr .22's to 522 grain 45/70's, all bottom pour. Some moulds like to be pressure cast with the mould in contact with the spout and some like to have ½"-1" drop between the mould and the spout. I can successfully cast nearly all with 700-750 degrees. Occasionally, I have to run the temp up to 800 degrees. I have a good thermometer and I use it to monitor the temperature.

I suspect that frosted bands (as opposed to frosted bullets - these are two different conditions) are caused when your mould blocks are too cold and the metal is too hot for that cold mould. Frosted bands are nearly always an indication of an undersize area of the mould (as you have found). Frosted bullets look a bit different from bright bullets but are not detrimental in any way. In fact, many of the people who use Lee Liquid Alox believes that the frosted bullets hold more lube (a GOOD thing).

Dip the corners in the bullet melt after it is up to temperature and hold there for exactly two minutes. That will bring the block up to heat and you should soon start to cast good bullets.

If you have a set of large blocks with a single cavity, it is a bit more difficult to keep it up to heat. It is EXTREMELY important to get a proper and consistent cadence when casting.

After reading your post, I believe you are CLOSE to doing well with that mould but need just a bit more "tuning" in your procedure.

Persevere and good luck.

Dale53

[dragonrider]

Welcome to the forum. I agree with Dale, your mold is too cold, also you lead to too cold, get the temp up to 750 at least. My best boolits come at temps of 750 to 800.

[SharpsShooter]

Same here....mould is too cold. Run the pot to 750-800 and after a good pre-heat, pick up the pace and cast. Also try allowing the alloy to fall an inch or so to the sprue plate, hitting just off the side of the pour hole. Often it will create a swirl of hot alloy and fill out those bands. Frosty boolits are ok, usually having less weight variation. BTW, the frost wipes off with a quick rub using a simple paper towel.

SS

[lovedogs]

Just an idea about your problem, may be right and maybe not. I also use a bottom pour, a Lee 4-20. When I pour 500 gr. .45-70 bullets there's a "sweet spot". It takes a bit of tinkering to get them just right. Too cold and they don't fill well, too hot and they get frosty. I know frosty doesn't hurt but my weights are more consistent when it's between cold and frosty, at the "sweet spot". If I'm running just a hair too cool my spout freezes up, also. A brush with a propane torch will open it right up, as you mentioned. So far I've not mentioned anything new. The other thing I've noticed that no one has mentioned is ventilation. I've found that if I have a fan blowing towards the pot to push fumes to my exhaust fan or if I try to cast outside where a breeze can hit it I get the frozen spout, also. If all these other ideas don't help you might check this. It helps me to monitor air flow around the pot. Maybe it'll work for you, too.

[lurch]

Thanks for the input. I will try craking up the heat & casting speed and see where that takes me with the WW & 2% Sn and let you all know how it works out. What was throwing me was that I was getting good fill at the lower temperature and then the frosted bands started as the mold got hotter. Seemed to me at the time like it may have been shrink back - but then again, maybe not.

Also, to answer Dale, the single cavity 44 mold is one of the small block jobs that isn't available anymore. That is the first mold I got when I got my 44 back in the mid 80's (oh those college days...) and started casting with my father's setup. Didn't have any trouble with it then, but it's been idle a few years and that was a different set of equipment and alloy. I'm just now starting back into casting after probably 20 years away from it. The signicant other is starting to look at the bills for the equipment (few molds, pot, sizer & dies, etc.) and well... [smilie=1:

FWIW, I emptied the pot last night and dug out some No. 2 (approximately anyway) alloy and tried the 358495 with that batch of alloy. I was able to get good bullets - nice & shiny with good fill out. They are dropping .359 or just a little fatter and weigh a pretty consistent 145gr. Using No. 2 seems like such a waste of the alloy for plain ol' practice wadcutters though with metal prices going where they are.

[Dale53]

lurch;
I predict that you will keep after the .44 mould with our suggestions and you will find WW+2% tin will give you near perfect bullets at a somewhat higher temperature.

Dale53

[Marshal Kane]

Lurch,

I have a bottom pour Lyman Mag 20 too and found my best casting temperature with ww/2% tin is at setting 9 1/2 which equates to about 775F. My mould shelf is set so that the mould sprue plate is about 1/4" from the spout. Less heat loss as the alloy transfers from pot to mould and also allows room for the alloy to form a lump on top of the sprue plate without touching the spout.

My mould is on the pot's warming shelf as soon as I begin to heat the pot. Following fluxing, I cycle all cavities in the mould at least four times (dumping everything into my sprue box) before actually attempting to cast. The bullets in my Saeco and Lyman mould tend to stick a bit when the temperature is just right. If not, the bullets just drop out so I cycle the cavities until that point is reached.

Hope these tips help. The Mag 20 is a terrific tool once you get used to it.

[lurch]

Well, you guys were definitely right. Things were too cold. I cranked it up to about 750F and started casting some of the .38 wadcutters after a little mold pre-heat. It worked great and the sprues were much easier to cut though there was a tendency to tear a little bit, but not badly. Also looks like I'm going to have to try some of that fancy bull plate lube at some point.

One thing that was a little troublesome at this temperature was oxidation and dross. I could barely keep up with the dross formation (not the tin oxide scum that forms and is easily fluxed back in the melt, but real dross) and was getting a lot of inclusions in the bullets that caused a bunch of rejects that were otherwise perfectly fine. The only way I got it under any sort of control was to throw a couple of handfuls of used walnut hull tumbling media in the pot to cover the melt about 1/4" or so. Made a heck of a stink that was not looked too kindly upon, even after lighting it and burning most all of the smoke. I cast in the garage and I'm told I had the whole house smeeling like the fire department just left.

Any thoughts on better ways to control dross formation at the higher temps?

Thanks for the help sor far. I just cranked out about 500 or so this evening and that's certainly a lot better than I was doing. :-D

[Dale53]

Keep in mind that there is certainly more than one way to "get there". After that is said, I fill my pot (20 lb RCBS) with CLEAN metal. At the same time that I turn the pot on, I place my mould on the hot plate at a predetermined temperature. I do something else while bullet metal and mould are coming up to heat. It takes 30-45 minutes for this to occur. I flux the metal ONE TIME. I use Carnauba flakes as supplied by NEI or LETS Casting Flux from "The Antimony Man". Bill Ferguson, the Antimony Man, is a metalurgist and had/has a short treatise on fluxing. You might want to write him and ask. He, as I remember, stated that most used entirely too much flux. At any rate, after that suggestion some years ago, I reduced the amount of flux (use only a pinch or so) and I immediately had better general results.

I bottom pour and only flux the one time. I run the pot empty and then, the next time, I fill, flux once, and run another pot. I use mostly WW + 2% tin and do not have a oxidation problem. Understand, I only use clean metals in my casting pot. All used metal (ww's, junk lead, etc) are smelted with my turkey cooker and dedicated 80# smelting pot. After marking the ingots (½, 1 lb, and 5 lb) I stack them up for use with the casting pot. I, of course, flux my smelting metal before skimming and pouring into ingots.

Dale53

[Marshal Kane]

. . . It worked great and the sprues were much easier to cut though there was a tendency to tear a little bit, but not badly.

Lurch,

Just a bit of advice to help cast better bullets:

Let the sprues harden just a bit more before cutting them. Torn sprues are caused when the alloy is still too soft to cut. This results in bullets that are out of balance and bullets with varying weights, due to the loss of alloy from the pit. Also, if any of the alloy from the sprue adheres to the bottom of the sprue plate, it can deform the base of your bullets since the sprue plate will no longer be flat.

Glad to hear things are going better for you.

[lurch]

Agreed on the lead sticking to the sprue plate - not terribly conducive to flat square bases - done that before. That said, I was not getting "hunks" stuck, just a little "wash" for lack of a better term. It cleaned right up with some heat and a good rubbing. Next time I get the stuff out, I'll slow down a bit more before cutting the sprue. As it was, I would drop the bullets, refill the mold and then roll the just dropped bullets looking for obvious flaws. Then I would cut the sprue, drop the fresh ones and repeat. I'm guessing something like 15 seconds from fill to sprue cut. I could cut simply by grabbing the mold and pushing the sprue plate with a little thumb pressure. Before I was using a dowel to cut.

Also, the next time I go at it, I'll try the reduced fluxing and see how that goes. I'll probably try using a wooden stick too to stir the pot to see if I can get any more of the crap out of the metal since several others here seem to like that method. I have maybe a little less than half a pot full of the gunked up stuff left so if it is too hard to clean up, it's not a terrible loss - probably turn it into sinkers at that point. I'm not sure where all the gunk came from since the other times I've used that batch, things were pretty clean. I'm pretty sure the condition of my pot is not helping too much either since when I got it, the rust it it made it look like a basket case. I was able to get it all (?) out electrolytically but the surface has a lot of pretty ugly pits in it that seem to me might like to hold on to crud and not let it come to the surface too well.