Testing BHN and finally reread instructions

[Mike W1]

Have a LBT tester from when he was still in AZ so I've had it awhile. Been testing some sample's and thought it might not be a bad idea to read things over again. Amazing how much I'd forgotten including it's a good idea to take 3 readings and average. However here's some points the author made that might give you guys all something to argue about!

"For maximum accuracy, calculate the average for at least three readings.

BE SURE TO MOVE PENETRATOR TO A DIFFERENT SPOT FOR EACH TEST, KEEP INDENTS SPACED
FAR ENOUGH APART THAT COLD WORKING OF FIRST INDENT DOES NOT INFLUENCE
SUBSEQUENT READINGS.

Space 1/16 inch apart for hard alloys, 1/8 or more for softer alloys.

If the first reading is lower than subsequent readings, disregard it. Even with extreme care in flattening bullet
bases and hand crushing any remaining smal1 flaws the first reading is normally lower than average.

Lead alloy hardness is determined more by cooling rate and ageing temperature and time, than by alloy content,
consequently, hardness readings cannot be used to determine alloy content.

Lead alloy hardness constantly fluctuates with temperature, approximately 4 bhn within the temperature range
of 0 to 100 deg F, softening at higher temperatures, and hardening at lower temperatures.

Regardless of alloy type, bullet hardness is virtually identical all the way through. No alloy or method of
hardening will produce a hard ‘skin’, and softer core, as many believe.

Hardness of air cooled, large diameter bullets can vary up to 2 bhn from side to side due to uneven cooling.
We have never encountered hardness variations within individual bullets that had been cooled by water
quenching, whether quenched after casting or heat treatment."

[runfiverun]

no argument from me.


they did miss a few points on alloy's showing softer/harder depending on the alloy's actual make-up.
two alloy's the same as far as sb-sn-pb but with the addition of a grain modifier or another metal in amounts leas than 0.5% can give you an altered reading, but as soon as you mix it with another [un-cut] alloy it shows it's actual major content make-up.
so take the bhn at face value, and not read anything into it.

[bangerjim]

Bhn is definitely relative! Use it as a guideline.....not the gospel.

I always do 3 to 4 tests in different spots on an ingot when testing with my Cabine tester. And use the average reading. Close enough "fer gubmint" work.

bangerjim

[Mike W1]

For my purposes I've only hoped to get a mix in the general ballpark but I was really surprised at how much leeway there is in those readings I've taken over the years. Guess just to keep myself happy I'll be a lot more meticulous in my method. On the other hand if my metal is anywhere near the 12-16 mark that I want that definitely close enough. It ain't like I shoot a handgun all that well anyhow and the paper isn't gonna know the difference! Gonna keep a close eye on those test slugs that I both air dropped and water quenched just to see if I can detect any difference's in em'. Keeps me out of the bars if nothing else.

[Mitch]

I have the lbt tester and very happy with it.i agree hardness is a thing that need not be as close as one might think.as said here many times fit is king.a range of 3 or 4 bhn is close enough for my needs.

[melloairman]

I have a Cabin tree tester . And shoot air rifles . I have 5 rifles that I need to keep the bhn at no more than 10-12 bhn or fps and accuracy go out the window . And 10 rifles that do not care what the bhn is . So I use it to keep my lead separated into basically two groups . 1 under 12 bhn and 1 over 12 bhn . And I have no problems . The other use I have for it is . If I cast some 15 bhn lead I can test it and use it in the under 12 bhn rifles until it gets above that point in bhn . It is the barrels on the rifles that is dictating the strength or hardness of the alloy that can be used . And since I am either paper punching or metal pounding expansion in not a issue .Marvin