First, some changes in your lead bullet casting technique may be required when casting the long, heavy .40 or .45 caliber bullets as compared to casting round balls. You may need a larger capacity lead pot, and the temperature of the lead may need to be higher. You must hold the lead dipper to the sprue plate for a longer time to assure all air is vented from the mould and the mould is filled. To obtain good castings, the mould and lead must be maintained at a uniform temperature. A large capacity lead pot helps keep the melted lead or lead alloy up to temperature. At least a twenty-pound capacity electric pot is required. The larger the capacity of the pot, the less effect the addition of new metal to the pot has on temperature. You may have to wait on the heat source to bring the temperature up to the required level after replenishment.
The purer the lead, the higher the required casting temperature. Proper casting temperature for the lead or lead alloy you are using may be found by trial and error. It will vary according to the speed with which you cast. A thermometer in the lead pot will help in assuring uniformity. A light blue color on the top of the lead when casting pure lead (commercially pure as most lead sheet is) is a good indicator of proper temperature.
Most shooters have found that using the bottom pour spout on an electric pot is unsatisfactory. The small cast iron ladles available produce the most uniform-weight bullets.
REMEMBER THESE SAFETY CONSIDERATIONS: The melted lead is very hot and you must observe safety precautions such as keeping all skin covered and wearing a face shield. Hot, solid lead will burn exposed skin long after it cools to the solid state. Fumes from melted lead are hazardous, and all casting must be done in a well-ventilated area. NEVER allow water to come into contact with melted lead, as it is rapidly converted to steam and an explosion occurs.
Almost any visual defect indicates a bad bullet, and it may as well be rejected as you cast. You want as perfect a bullet as possible to shoot at the extended ranges, as the slightest defects are magnified several times during the bullet's flight to the target. The time and patience spent in producing good bullets are rewarded with good groups and/or the ringing of the silhouette.
Your acceptance criteria for good bullets should be:
- No wrinkles or surface defects
- Clean cut, flat bases
- Weight variation should not exceed three grains
- Good bullets will show the mould surface machining marks
- Finished bullets should be weighed and segregated in one grain-variation groups within the three-grain limit
Bullet casting must proceed as rapidly as the freeze point of the lead in the mould allows. Keep the mould up to proper temperature. Bullets should be dropped onto a soft surface such as a cotton towel (no plastic/polyester in the cloth), and the surface should be well padded so no damage occurs to the bullet. Keep the mould clean and keep the lead pot hot, and you really will find that casting the large bullets is no more difficult than casting round balls.
The finished, segregated bullets should be placed in styrofoam pistol cartridge boxes with styrofoam on the top and bottom of the bullet. These styrofoam boxes are inexpensive and excellent for transporting the bullets. They can be reused many times.