The test calls for pressing a 10 mm ball into the lead for 30 seconds with a force of 220 lb. (a 100 kg weight).
Then enter in the diameter of the ball, the diameter of the dent, and the weight of the weight you used into the familiar Brinell Hardness Number Formula. Or use this online calculator:
The cheap tester I use consists of a C-clamp with an epoxided on 1/4" washer and an epoxied on 3/8" ball bearing on the top jaw of the clamp. The epoxy and washer helps keep the ball from rolling and shooting out to the side sometimes.
The lead to be tested sits on a 4" x 4" piece of 1/4" steel plate on top of a bathroom scale near the edge of a table or bench. Whatever the scale reads with the steel plate and the lead sitting on it, the bottom jaw of the C-clamp is hooked under the edge of the bench, and the ball is cranked down into the lead until the scale reads 220 lb. more than what you started with. One Mississippi, two Mississipi, three Mississippi, ...
After 30 seconds, uncrank the C-clamp, measure the dent, calculate.
I got about 5 for some pure lead I bought, and my air-cooled wheelweight ends up in the 10-13 range usually. Had a funny batch of wheelweight with peacock-colored dross that I eventually got rid of and the lead left behind gave me a BHN of about 6.