I just received two new molds from Tom at Accurate. I designed 43 257H and ordered a 3 cavity iron mold, 43 249H went into a 3 cavity aluminum. They may answer several burning questions.
The first was how good Tom’s iron molds are. The answer is they are every bit as good as his aluminum molds. Which is to say they are super.
There is a soft spot in my heart for iron molds, they are very forgiving of exact temperature. When adding metal to the pot the temperature will drop 50 -100 F, an iron mold keeps right on casting perfect bullets. The aluminum mold goes back on the hotplate because if the alloy is off temperature, half the bullets will be rejects.
The molds are both perfect for sizing 0.430 casting 0.4305 – 0.431 in 2% 6% alloy.
43 257H is probably going to get the most use as it is a Keith type with a front band dimensioned for my revolvers.
The big change is a 0.020” bevel base. The advantage of a bevel base is the reduction of incomplete base fill-out. Incomplete base fill-out seriously compromises accuracy, giving wild fliers. Base fill is easy to evaluate, but the rejects represent a waste of time. A bevel base gives better base fill and fewer rejects, but a normal size bevel base reduces the base band width which can limit maximum velocity. The question is how small can you make the bevel base and still get the casting advantage.
Tom’s excellent machining makes it possible to make a very small bevel base. A 0.020” bevel base is very small, so it does not detract much from the base band, in fact you have to look closely to see it.
I have not accumulated much casting with the new mold but the casting results are apparent. Base fill is much improved, base rejects are way down over the plain base molds. I will try to quantify this later with a side by side casting run with a plain base mold.
Accuracy – we will see.
43 249H 3 cavity aluminum
I wanted a replacement for the Lyman “oil drum” 44 bullet #429352. I no longer have that mold, it was traded in a moment of weakness, and I only have a few left. The resulting bullet looks like a LBT Ogival Wadcutter and should perform just fine. It has more engraved length than #429352, seating depth like a 250 grain Keith SWC. It is designed to fly fast and hit hard at short range.
The aluminum mold performed as expected. It runs best hot, with alloy at least 100 F over liquidus. If I keep up the casting rate quality is excellent. I tried running the two new molds together, no go the iron mold was quite happy but the casting was too slow for the aluminum blocks.