I was casting Tuesday & Wednesday with 4 new pieces of casting equipment so I didn’t have high hopes for success this time.
1) New furnace, a RCBS ProMelt-2
2) New mold, SAECO #955 4 cavity 255 grain for 45 Colt.
3) New single element hot plate, to preheat & keep the heavy iron mold hot.
4) Alloy metal - mystery metal of unknown lead composition.
The problems I encountered in casting and with the cooled bullets:
1) Of the thousand bullets cast all show frosted except for the wide base drive band it’s mostly shinny.
2) A large percentage cast with a slightly rounded base edge.
How would I be able to tell if the mystery alloy was contaminated with zinc?
The new furnace was much slower to melt the lead than my old LEE Pro 20#. The Pro Melt-2 is 25# pot. That’s a 25 percent increase in metal weight to heat and melt.
This casting session was the first time I’ve use a hot plate to preheat a mold. I put a 4”x8” thin 1/16” thick sheet of steel over the burner coil tube a heat spreader and ran the hot plate at a low #3 heat setting.
I use a LEE lead hardness tester on all the 6 one pound ingots cast from the last inch of lead from the bottom of the furnace pot. BHN 8 is as low as the LEE reference chart goes and my measurements show the alloy is BHN 8 to estimated 7.8
I was lowering the pot temp from a high 845* because at the high temp I couldn’t keep a sprue puddle on the cutter plate it rolled off like water.
At ~720* I could keep a Lima bean sized puddle on each inlet hole, the puddle was usually connected to the next in one finger length strip.
A random sample of as cast bullets averaged weight is 263.1 grains and diameter is .4559” to .4564”
Next time I’ll try to cast at hotter temp to get more diameter shrinkage and lighter weight and use a known alloy instead of scrap.