Lee's 356-120-TC Mold Questions

I haven't been able to find any details through a fairly thorough search, so if I have managed to completely overlook the answer here, it's because I wasn't looking for the right thing....

Anyway, what weight does the Lee 356-120-TC drop when cast with wheel weight alloy?

How hard is it to keep the 2 cavity mold hot between pours? After I drop the finished bullets, how do I get the mold hot enough to cast again?

Do brand new molds need to be cleaned in any special way before use, or is a thorough de-greasing (I'm thinking nonchlorinated brake cleaner) enough?

Thanks in advance!

I have one...they weigh 125 grains w/ WW metal when cast.

I've never had an issue keeping the mold hot between pours. You may have to cast a few before it gets up to proper temperature; after that it will hold its' heat nicely.

With its' first use I spray the blocks with carb cleaner and wipe, before use, then apply lubricant to the pins as per Lee's instructions.

It is a good mold design and makes excellent 9mm Luger bullets. Some dislike it because it has a very small bevel base.

I am fairly new at this, but I can tell you what I do. I bought a brand new lee mold. The only thing I did was scrub it real good with warm water and dawn. I used an old toothbrush. The molten lead keeps the mold hot. I did best when my lead was between 650-700 degrees. I used a thermometer to tell. I heated my mold with an old hot plate. The worst thing you can do is overheat your mold. This will warp your sprue plate. It takes a little bit to get into a rythym, but it is not that bad. If you don’t get your mold hot enough to start, no worries, after a couple attempts the hot lead will get it up to temp. I hope this helps. Anymore questions, just ask.

I forgot something. I used a tiny bit of 2-stroke oil on the alignment pins, and a tiny drop where the sprue plate swings. Don’t get any in the cavities. If you do scrub it out with dawn

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Originally Posted by OTShooter

I haven't been able to find any details through a fairly thorough search, so if I have managed to completely overlook the answer here, it's because I wasn't looking for the right thing....

Anyway, what weight does the Lee 356-120-TC drop when cast with wheel weight alloy?

How hard is it to keep the 2 cavity mold hot between pours? After I drop the finished bullets, how do I get the mold hot enough to cast again?

Do brand new molds need to be cleaned in any special way before use, or is a thorough de-greasing (I'm thinking nonchlorinated brake cleaner) enough?

Thanks in advance!

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Your dropped weight and diameter will vary depending on your particular alloy and mold. The Lee molds tend to vary a bit and the sizes and weight may not be exactly the same as someone else's mold.
Normally the weight is 120-125 grains unless using a very soft alloy.
Follow the package directions for heating up your mold. Cut the sprue when the puddle on top of the sprue plate gets frosty and hardens. To soon and you get smears on top of the blocks and the bottom of the sprue plate. Wait too long and the sprue gets hard to cut. A little experimenting will tell you when is the best time.
Normally, you won't need to worry about keeping the mold from cooling off after you get it up to temp. If anything, you will find you need to cool it off after a while since the sprue puddle will take longer and longer to harden. Keep a moist washcloth near your table and put the bottom of the mold on it for a few seconds to help with excess temperature.
Others have given you good advice for cleaning and lubricating your mold.
Make sure you keep the screw that holds the sprue plate snug so you don't get flashing on the bottom of the boolit. Some of those screws are a left hand thread and and the mold will usually be marked LH on the block somewhere.
Personally, I water drop my boolits when I am going to use them in a 9mm. They don't necessarily need the extra hardness but it doesn't hurt anything.

Mine is a six cavity and drops we around 124 gr. I can size them to .357 easily. The 2 cavity molds will get hot fairly fast. I'm not one to be concerned about frosted boolits, but if I start getting them I'll slow my cadence somewhat and maybe turn the heat down a bit. I am a bit picky about the finished product, especially the bases. If all you are going to shoot is informal paper or steel or something a few light wrinkles on the nose won't be the end of the world. Did I say the bases needed to be flat? If it sizes well and the driving bands look good and you have enough lube you should be good to go. Remember that fit is of utmost importance. A boolit that is too small will give nothing but grief. Better to be .001-.002 over bore diameter.

The Lee 356120TC (not TL) is my choice for 9mm. Cast/shot ~ 40,000 so far from a 3/3/94 alloy, sized .357. Feeds is every 9 I have tried it in.

What is a good COL for this bullet with Win 231?

You need to do a "plunk test" to see how it fits.

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Originally Posted by Tom W.

You need to do a "plunk test" to see how it fits.

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Did a plunk test - passes at 1.10" sized .357 (cerro cast the barrel at .358)

If I calculate based on case volume using load data for similar round of the same weight it comes out to 1.06" min.

Is it better to go longer and just cover up the lube groove or try to match published data more closely?

I like to go as long as I can if there are no feeding problems.

I load that boolit to 1.057" OAL and crimp to .379-.380"
many, many rounds fired using BE, 231, Red Dot etc. Moderate loads, usually.

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Originally Posted by pastera

What is a good COL for this bullet with Win 231?

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Every chamber is going to be different. Plunk test. Do they fit in the magazine. They should plenty of length in the magazine.

SHiloh.

I load to 1.055-1.057" for my guns, usually over 6 gr HS6 or 3.8 of WST. Lots of other powders work too.

I just went out to the shed and measured some loads... 1.060 -1.062

OT shooter, if you can go the extra $20 get the 6 cavity (about $40 from Titan reloading). The production rate is better and I think the mold quality is better also the cam action sprue cutter is great! I ran mine on Saturday and made 720 keepers in a relaxed 2 hours. Mine drop at .358 and 123 grains. Tim :bigsmyl2::bigsmyl2: good luck and good casting.

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Originally Posted by tward

OT shooter, if you can go the extra $20 get the 6 cavity (about $40 from Titan reloading). The production rate is better and I think the mold quality is better also the cam action sprue cutter is great! I ran mine on Saturday and made 720 keepers in a relaxed 2 hours. Mine drop at .358 and 123 grains. Tim :bigsmyl2::bigsmyl2: good luck and good casting.

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I agree with this^^^^^^^. The 6 cavity is way more productive than the 2 cavity and is built better.
The quantities tward mentions are easily obtained at a comfortable pace.

I would recommend buying the 6 cav mold. Clean it with dish soap or carb cleaner. Fill your pot with lead, lay the mold across the top of the pot and cover it like a tent with aluminum foil. Turn the pot to max heat, get a cup of coffee and come back in about 20-30 minutes. Your mold and alloy will be just perfect to start casting. Fill the mold, wait for the spru to "flash" (harden), cut the spru and examine the bullet bases (this is the most important part of the bullet) and cull the bad ones back to the pot. You normally will have very few bad ones. Do NOT admire or examine your bullets at this point. Just fill, cut, examine bases, dump and repeat. If you do this mold temp and bullet uniformity will be excellent. If after a few minutes casting your sprus seem to take a longer time to flash turn your pot down a little till you reach a good steady state casting temp. That's all there is to it.
I use the Lee 120 TC 6 cav all the time. An hours worth of work gives me 600-700 good bullets which are the main bullet I shoot in my K-38. Good luck to you.