Little boolits in big blocks.

[fourarmed]

I'd like to get some advice from you .22 casters. I have a 4-cavity Lyman in 311252, which is a 77 grain RN for the .32acp. Those little guys don't put heat into those big blocks very fast. What do you do to get a big mold for a little boolit to fill out nicely? I'm considering preheating it on a hotplate. What do you do?

[felix]

That is one hell of a problem, getting enough heat for these little suckers. You HAVE to do the BruceB technique to get boolits good enough to shoot. If the ambient is 95 degrees, that won't be too hot to cast. If much cooler, you must NOT cool the sprue plate. Iron molds are the way to go here, given the choice. Corky and I, and maybe Dan too, are contemplating having David Mos make us some molds (group buy) that have 4 cavities per 2 cavity block. We are waiting for a good design to appear. ... felix

[Bullshop]

Fourarmed
Read the post on possible new 22 design. I wrote a bit about this in a couple different posts.
BIC/BS

[beagle]

That's a really big problem with small bullets. I cast a bunch of .22 bullets and some are HPs in the bigger RCBS blocks. Its a hassle to keep the mould temp up just casting with one cavity in the bigger RCBS blocks.

Obviously, you need to preheat the mould on top of the pot prior to casting.

Then, insure that the mould rests on a non heatconductive surface between throws. This helps retain the heat of the mould.

BruceB's technique then comes into play...cast as fast as you can to keep the temp up.

I have several moulds that are just of the right size...the cavity size balanced to the block size.

A small hotplate may help but after you get rolling and the mould up to the proper casting temp, I'd say it would be in the way.

If I was casting a bunch of those on a regular basis, I'd have the outside of the blocks scaled by a good machinist to eliminate some of the excess mould block metal and then coat with spray moly which will help to retain some of the heat.

This is kind of an unusual problem when normally we're trying to keep the mould blocks cooler for good casting with the larger calibers. On them, I've experimented with using electrical heat sinks and it works but is kind of bulky to handle./beagle

[45 2.1]

A simple fix for this problem is: preheat your mold by diping one end (both halves evenly) into the melt until the lead doesn't stick to it. I've done this for 30 years with absolutely no damage to my molds; steel, mehanite and aluminum.

[slughammer]

I only have a 10lb pot so the opening is not that big. I started putting 3-4 molds into a toaster oven at the same time I fired up the pot. I leave the door open and the handles sticking out with a bent cookie sheet acting as a heat shield. I used an RCBS 32-98 SWC for the first time and using this technique I was getting good boolits from the get go. I use a desk top fan to cool the sprues when its hot and I watch the clock for cycle time between each sprue cut.

[boogerred]

i use a hot plate with a 1/4" steel disc to preheat my molds. i always start with the heaviest first and by the time get to the 85 gr 32 cal i get good bullets in 3-4 casts. works for me but you have play around to find the right timing.

[Bass Ackward]

Well, I use logical steps to keep the mold blocks hot as other describe. I also use the aluminum mold trick in that I spray molly in my cavities. Adds just enough insullation that I can avoid dipping.

[castalott]

I had a similiar problem casting with 2 cavity molds on my machine. The extra metal of the machine was a heat sink. Very fast casting helped but not enough. I ended up painting the molds and the attachment areas white. Most cast iron molds are a dark color and dark colors radiate heat... This is an advantage with most molds..but not all.

The white color did help. I would consider painting the handles where the molds attach white also..That would act as insulation for the heat path..Anything to slow heat transfer from the mold...

I would also leave as big a sprue as possible.

Dale

[D.Mack]

I'm with 45 2.1. I dip the bottom ends in the melt, alow the mold to heat, remove, and give them a minute to transfer heat evenly, and begin using a good size puddle. I also turn the heat up a little. Thiis will of course void the warrantee, but only if I tell them, but after years of doing it this way, my concern with the warrantee is how the mold comes out of the box, not with how I might abuse them later. D.M.

[Bent Ramrod]

Fourarmed,

Add me to the list of those who dunk the bottoms of their large-block, small-cavity molds in the molten lead until it no longer sticks. I do this with castings, however imperfect, inside, and have never seen any of the warpage that is alleged to happen.

Once the blocks are up to temperature, I do more than leave as big a sprue as possible; I dump a bunch of the lead on the sprue plate. I figure you have to add the equivalent amount of heat to the mold each time that larger bullets would add, and the only way to do so is to put a mess of it on top. Makes for kind of messy casting, but I have fewer rejects that way.