Veral Smith suggests in his book that a hardness tester should be the last gadget you buy. If you will water drop your bullets from the mold, and if you use straight wheel weights, the hardness will be somewhere around 20 BHN which is plenty hard enough for most purposes.
For water dropping I've found that a big cheap kitchen sponge works great. Fill a five gallon bucket three fourths full of water. hold the sponge under the surface of the water and squeeze most or all of the air out of it. Then allow the sponge to come back to its normal size while holding it under water. This assures the sponge will be completely waterlogged. It will barely float. Now when you drop bullets onto it it will do a slow roll and drop the bullets onto the bottom of the bucket, but only after they have hardened enough by the sudden cooling so that they won't be deformed. It also hardens wheelweight lead to 18-20 BHN range.
