- Joined
- Aug 1, 2007
- Messages
- 177
- Reaction score
- 124
I must be getting bored with the enforced idleness of Covid-19 isolation. Granted I have built two rifles and get to the range about once a week, but having been a free-range retiree I still feel stifled.
A year and a half ago the Boulder Rifle Club had its summer shoot and barbecue, with a prize table for winners to draw from. Some items were purchased for the table, many were donated. On my second pass by the table I picked up what I thought was a six cavity 50 cal Lee mold. When I got home I found it was a twelve cavity mold. It is an interesting design, with six holes in the sprue plate, each feeding two cavities stacked closely one above the other. The resulting cast is two 50 caliber balls cheek by jowl, which need to be separated. I set each pair on a hard surface, placed a large heavy knife blade on the isthmus, and gave the blade a whack with my mold mallet. The result was one ball- the bottom one in the mold- with one sprue mark, and another with two marks.
The bottom cavity balls - the ones with only one small sprue mark- have a weight range of 174.0-175.0 grains. Mean is 174.3, median is 174.4, mode is 174.4. Mean, median and mode all being close together is a good sign, and contributes to the low standard deviation of 0.32 grains. I would happily shoot any of these balls for competition or hunting.
The top cavity balls- with two marks opposite each other- showed more dispersion. They were heavier than the other set, with a weight range of 176.1- 178.4 grains. Mean is 177.0, median is 176.8, with mode at 176.2. The greater range, mean, median, and mode result in SD of 0.78 grains. Actually not too bad.
The fly in the ointment is the wide range between the lightest one sprue ball and the heaviest two sprue ball, 174.0- 178.4 grs. For best accuracy groups, shoot each type separately, not aggregated.
The mold operated well, no problems with the cut off plate, halves aligned easily, castings dropped out easily. I had washed the mold well with detergent, then sooted it heavily using a long stem barbecue lighter. One drawback I did find was the weight of the filled mold, which was troublesome to my arthritic thumb joints.
A year and a half ago the Boulder Rifle Club had its summer shoot and barbecue, with a prize table for winners to draw from. Some items were purchased for the table, many were donated. On my second pass by the table I picked up what I thought was a six cavity 50 cal Lee mold. When I got home I found it was a twelve cavity mold. It is an interesting design, with six holes in the sprue plate, each feeding two cavities stacked closely one above the other. The resulting cast is two 50 caliber balls cheek by jowl, which need to be separated. I set each pair on a hard surface, placed a large heavy knife blade on the isthmus, and gave the blade a whack with my mold mallet. The result was one ball- the bottom one in the mold- with one sprue mark, and another with two marks.
The bottom cavity balls - the ones with only one small sprue mark- have a weight range of 174.0-175.0 grains. Mean is 174.3, median is 174.4, mode is 174.4. Mean, median and mode all being close together is a good sign, and contributes to the low standard deviation of 0.32 grains. I would happily shoot any of these balls for competition or hunting.
The top cavity balls- with two marks opposite each other- showed more dispersion. They were heavier than the other set, with a weight range of 176.1- 178.4 grains. Mean is 177.0, median is 176.8, with mode at 176.2. The greater range, mean, median, and mode result in SD of 0.78 grains. Actually not too bad.
The fly in the ointment is the wide range between the lightest one sprue ball and the heaviest two sprue ball, 174.0- 178.4 grs. For best accuracy groups, shoot each type separately, not aggregated.
The mold operated well, no problems with the cut off plate, halves aligned easily, castings dropped out easily. I had washed the mold well with detergent, then sooted it heavily using a long stem barbecue lighter. One drawback I did find was the weight of the filled mold, which was troublesome to my arthritic thumb joints.
