Gents;
This is one area where I do have some experience. Describing the following method may make some of you doubt the claimed results, but believe me it works, and many of our fellow casters have tried it out and agree. I also have some credible witnesses! The method is now called "doing the BruceB" on the Cast Boolit Board at aimoo.
Using a SINGLE two-cavity mould, it's possible to cast well over four hundred GOOD bullets per hour. A four-cavity Lyman will usually deliver as many as 1000, and a single-cavity can cast something over two hundred very nice bullets in sixty minutes. These figures include bullets from a 100-grain .30 caliber to the 550-grain bullets for a .50 Sharps'. By "good" bullets, I mean bullets having a maximum weight spread of less than one grain in a 200-grain .30 caliber design, and I've had less spread than that in batches of several hundred 365-grain .416s from a single-cavity RCBS mould.
The secret is speed-cooling the sprues on a wet cloth pad sitting in a shallow dish of water. As soon as all the drawing-down of alloy into the cavity has ended and the sprue has solidified, even BEFORE it stops changing color, the mould is inverted and the sprue pressed against the wet cloth for just two or three seconds. This cools the sprue sufficiently that it will cut cleanly without smearing any lead whatever across the mould top. It also eliminates the time spent waiting for the sprue to aircool to that point. Using just one mould also eliminates the time wasted in the many hand motions required to put down one mould and pick up another one.
If efficiency and PRODUCTION is the goal, then minimizing hand motions is a key to success. Analyse every motion, and reduce them to the bare minimum. Such things as where the mallet is placed while filling the mould, where the sprue container is placed, EVERYTHING about the physical setup should be studied and experiments carried out to see what works easiest and quickest.
The cautions about water and molten lead deserve attention. In my high-speed casting, the shallow dish with the rolled-up cloth pad sits right beside the coffee can which I use for sprues. The high sides of the can prevent any spray or drops of water from reaching the sprues, and I watch the mould after cooling the sprue until ALL WATER has evaporated from it, and ONLY THEN do I cut off the sprue and drop it in the can. This only takes a very short time, and prevents water from being dropped into the sprue container. I also re-melt the sprues whenever the can starts getting full.
Incidentally, if ANY water gets INTO the melt, that is, below the surface of the molten alloy, there WILL be a violent reaction. Adding alloy that is wet or has drops of water in or on it will do this. However, a drop of water (sweat, beer) that falls ON THE SURFACE of the melt will just sizzle and bounce around until it evaporates. Don't believe me? Try it for yourself, cautiously.
I use an RCBS 22-pound-capacity pot, which I run virtually ALL the time at its max temperature of 870 degrees. My alloy is in 3-pound triangular-section ingots 10.5 inches in length (cast in an angle-iron ingot mould). To eliminate the "downtime" of waiting for the pot temperature to recover after adding alloy, I preheat several ingots at a time on top of the furnace above the melt. They get so hot that adding a 3-pounder only drops the pot temp about 30 degrees, and I just keep right on casting without a break. As the front ingot is put in the pot, the row of ingots is moved ahead one notch and a cold one added to the back of the line-up to start heating. More time saved!
An ingot is added whenever one will fit into the pot. Keeping the melt level high minimizes variation in the flow pressure at the spout, and I have no doubt that this is another aid to consistent bullets.
By doing all the above, my casting rate usually fills the mould four to five times per minute, or eight to ten bullets per minute from a two-cavity mould. This will vary a bit, as larger bullets take more mould-filling time and so does a 4-cavity mould. I kept time one day and filled a Lee single-cavity .30-130 mould 155 times in 30 minutes, and rejected only six bullets....and I am FUSSY about bullet quality. Note that fast casting, especially if we're water-dropping the bullets for quenching, minimizes temperature variation in the bullets being dropped and hence more consistent hardness after quenching.
The method woks fabulously. I hope this gives y'all some food for thought. If you want more peoples' experiences, search on Yahoo for "cast boolits" and come see us!
