Quick links to results and relevant information regarding specific tests:

Casting Method:

• At initial glance, LBT and SAECO tools seem to have the highest standard deviation. Throwing out the high LBT tool reading and eliminating the early test that was redone with a different batch of bullets closer to the testing date moves the standard deviation more into line with the Cabine Tree and Lee testers.
• Cabine Tree, LBT, and Lee tools appear to have been equally consistent within their groups for this particular batch of bullets. SAECO seemed to have more variance, due in part to conversion factors.
• SAECO and Cabine Tree BHN estimates were more dependent on user conversion from the raw data reading into a BHN number than the LBT and Lee tools.
• The Cabine Tree numbers could be more accurate with more “mapping” of the correlation between indent depth and actual lead hardness.
• LBT numbers were closest to the actual lab results, with all other tools measuring the samples as harder than reported by the laboratory. This is especially true if the “high tester” set and the early duplicate test are eliminated from the data. SAECO and Cabine Tree testers measured the farthest from the actual lead hardness.
• Cabine Tree tools produced the smallest extreme spread, while the LBT tools produced the largest. If the LBT high test is removed, then the SAECO would appear to have the highest extreme spread.
• The Lee tester appeared to produce the most readings that were both consistent and closest to the actual laboratory results. Although individually other testers came in with slightly smaller standard deviations and numbers that came in closer to calibrated equipment, the Lee appeared to have the best combination between the two areas.
• The differences in the SAECO numbers raised the question of if there was any correlation between the age of the tester and the BHN that was reported. A query was sent out to the SAECO users to determine if their tools were the older, metallic colored ones, or the newer, yellow anodized aluminum ones. Testers 5, 9, 12, 16, and 17 were reported to be the newer yellow testers. Testers 15, 26, and 44 were older, metal colored units. This information seems to indicate there is not a correlation between the jump in numbers on the SAECO'S and age of the tools. There has been no response from tester 37 yet, but at this point it is doubted the age of the tester (equipment) will shed much more light on any age to measurement connection than the initial responses already have.
• An experience that may be relevant to this experiment was reported by user Dye (with SAECO testers 16 and 17). He sent his testers back to the company when the measurements of one of his alloys did not come back the same between the two testers. When they were returned to him they still provided different readings. Although the deviance did not appear to be present for this particular alloy (in this test), Dye's experience may or may not shed light on other differences that have appeared between SAECO'S in this test. There simply isn't currently enough information collected to determine the cause of the differences beyond the shadow of a doubt. It could be simply that this alloy was harder than the "sweet spot" that this particular brand of tester measures accurately.

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     Here is the data on the hardness of the 10 bullets you sent to me. The indentations were made last Friday night which is as close to the Saturday date you requested as I could get. Last night I measured the diameters of each indentation three times as shown in the attached photograph. This is an extremely accurate measurement technique as it is done at 100X magnification. The indentations were made with a 15 kilogram force and using an indentation ball of 1/16 inches (1.587 mm) in diameter. Each bullet was mounted in a cold setting epoxy mounting medium. Then the surface of the mount using appropriate metallographic technique was gently shaved by about 0.010 inches to provide a flat surface to the indenter of the bullet nose.

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     These are not laboratory grade pieces of equipment; no one should think they are, no one could afford them if they were. What is important with these testers is consistency. It doesn't really matter if a lab tested piece of lead is 20 BHN and your tester says it's 18 BHN and someone else’s says 22. What is important for your handloads is that your tester ALWAYS says 18 BHN plus or minus about 1 BHN and the other guys always says 22 plus/minus 1. That's close enough for you to keep accurate notes and use it to assemble very consistent ammo from batch to batch.

     In these experiments there were nine different LBT testers. Of the 9 two were very clearly out of calibration, the remaining 7 testers where easily consistent enough for consistent BHN readings for cast bullets. The other two testers can be calibrated and should be. With the LBT testers if the two erroneous tests are removed the seven remaining average 19.0 BHN (the lab average was 19.8 BHN). With each of the brands tested if you throw out the various obvious erroneous readings (chalk these readings up to machine and/or operator error) they are easily close enough (accurate enough) for consistent cast bullets.

     I did an extensive long range BHN test with my 9" FA 357, many hundreds of rounds in 5 shot groups that took a year and a half shooting scoped from the bench at 150 meters. All loads where as identical as I could make them using only virgin brass, powder, primers and alloy from the same lot numbers. BHN changes ranged from air cooled WW @ 11 BHN to convection oven HT 30 BHN and many BHN ranges in between. My revolver shot the best groups with the lowest S.D. and E.S. at 17-18 BHN. A BHN range of 1 or 2 within the same group seemed to make no difference in grouping. Shooting a group with a wide variation in BHN (say 15 BHN to 22 BHN within the same 5 shot group) destroyed groups and opened up both S.D. and E.S.. Repeating the same tests over and over proved this out. Without a consistent method of determining BHN "ranges" this testing would not have been possible.

     So yes, these testers are a valuable asset to the bullet caster. Does my tester say an alloy is 18 BHN and the lab says no . . . its 20 BHN . . . Well, so what? It doesn’t matter as long as mine always says 17-18. Consistency matters, an exact match to lab results does not. If your casting technique is consistent enough to keep your bullets within 1 BHN and your BHN testing tool is consistent enough to measure within 1 BHN even the most demanding caster should be good to go. Alloy consistency is important for long range top end loads grouping and these tools are an important "aid" in assembling consistent cast bullet loads.

     So what do these experiment prove? The differences between the various testers, the simplicity of using the tester making consistent readings possible, the users ability to use the tester consistently and interpret the results. This test also has shown how close to the lab tested sample (most of) the various testers really are.
 

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