I was wondering about how Brinell hardness numbers should be interpreted. For instance, is the numbering linear. So, when comparing a BHN of say 16 to another reading of 20, is the reading of 20 actually 25% harder than the reading of 16? I was comparing two different bullets with the above BHN numbers and the BHN 20 bullets seemed much harder than the BHN 16 bullets, much moreso than I expected.