This Is Strange.

[buck1]

I have a saeco hardnes tester. When I check small 30 cal Flat nosed boolits I get a harder reading than if I check a 44 swc from the same pot.
A 30 cal boolit is #7 , wile the swc is #5. I cast them at the same sitting and repeated the test about 10 times. any ideas??

[felix]

No, Buck, it is not strange because immediate hardness is based upon cooling rate. The smaller boolit cools faster because it is smaller in mass, and thus will be harder. Wait a year or two (or much more, who knows) and then both boolits will be at the exact same hardness. ... felix

[Dye]

buck1
You didn't say how soon after you cast them that you was checking BHN. Let them set a week and check them again. I assume these are air cooled.
BE Careful Dye

[JDL]

buck1,
I have noticed the same thing with my .30 cal. and .458's that I cast last year. .308's check out as 14 while the .458's are 12.5 BHN.
Does it make any difference to check at the base instead of the nose?-JDL

[Shuz]

FWIW--When I check for hardness, I always make sure the mould is "up to temp" for casting good boolits, otherwise you just might be "quenching" the alloy in a cool mould. Also, because of the size concerns Felix mentioned, I always use .44 diam boolits for hardness testing regardless of the boolits I'm casting. Seems to work for me.--Shuz

[felix]

Shuz is correct in his thinking by using the same mold, same cavity for boolits to check for hardness using a typical punching tester machine. Personally, I don't like the idea and never bought one of these machines because I am not really after hardness per se, but after shearing strength numbers instead. If I were serious about this, I would have a barrel maker make me a 6 inch fat barrel section which is small in groove diameter, say 429 for 431 (or better boolits), lands at 005 high, throated with 6 degrees inclusive at one end, chambered at both ends (for an inch each) of the barrel at 436 so a boolit will drop in and stop, and then drop out after being pushed gently through with a flat ended ramrod attatched to a drill press. The maximum force on the drill press to punch the boolit through until it drops out the bottom (into the bottom chamber), is the magic number placed into a book describing the alloy. Actually, you would use a flat scale, which can hold the maximum number, as the drill press table... felix

[Scrounger]

Shuz is correct in his thinking by using the same mold, same cavity for boolits to check for hardness using a typical punching tester machine. Personally, I don't like the idea and never bought one of these machines because I am not really after hardness per se, but after shearing strength numbers instead. If I were serious about this, I would have a barrel maker make me a barrel which is small in groove diameter, say 429 for 431 (or better boolits), lands at 005 high, throated with 6 degrees inclusive at one end, chambered at both ends of the barrel at 436 so a boolit will drop in and stop, and then drop out after being pushed gently through with a flat ended ramrod attatched to a drill press. The maximum force on the drill press to punch the boolit through until it drops out the bottom (into the bottom chamber), is the magic number placed into a book describing the alloy. ... felix

I have always been impressed beyond reason with velocity numbers but Brinell numbers haven't made much of an impression on me. I do see the need for different hardnesses of bullets, from ww (10) to lino (22), and I understand how to control it. In particular I've had no interest in hardness testers. I've been more inclined to go by weight. If you have a particular bullet made of ww that weighs 244 grains, and the same bullet made of lino at 235 grains. It would be a simple matter to match either of those weights, or anywhere in between, by adding SB or PB to your bubbling cauldron of mystery alloy, and casting samples until you reach the desired bullet weight. Which would be the same hardness. Or am I missing something here?

[felix]

Close, Scrounger, but no cigar. There is no guarantee with scrap metals what is causing a weight variation. If you are dealing with only two metals, each pretty much pure, then you would be absolutely correct. For example, melting in some babbit of unknown constituents can cause havoc with weight contol. Is it tin or lead based babbit? How much final arsenic is in the mix? How much copper? All these minor elements will cause a significant shear shift of the final boolit, and might or might not alter the weight enough to really decipher anything concrete enough about what percentages are in the final mix. ... felix

[Scrounger]

Close, Scrounger, but no cigar. There is no guarantee with scrap metals what is causing a weight variation. If you are dealing with only two metals, each pretty much pure, then you would be absolutely correct. For example, melting in some babbit of unknown constituents can cause havoc with weight contol. Is it tin or lead based babbit? How much final arsenic is in the mix? How much copper? All these minor elements will cause a significant shear shift of the final boolit, and might or might not alter the weight enough to really decipher anything concrete enough about what percentages are in the final mix. ... felix

OK, but correct enough if using known metals? And for any shooting purpose except high lever research?
Besides, if I was right all the time, I'd be StarMetal, so I really don't mind being wrong...

[felix]

Naw, Scrounger, you're doing fine as is. In fact, I am doing the same thing with the metals I have laying around. A measuring device as described would be the only one of interest to me, should I get serious again about boolit quality. If I can kill/skip shotgun shells at a hunnert using a scoped gun, that's good enough for me. Offhand with lever guns at 50-60 yards is OK too. ... felix

[Gussy]

buck1, there's a chance that the cause is a flat nose vs a round nose. On my tester, a round nose will "spread" as well as indent. File a small flat and see if it changes.

Do not check the base!! At least not on a base pour. The center of ths base will check soft almost every time.
Gus

[Bass Ackward]

I have a saeco hardnes tester. When I check small 30 cal Flat nosed boolits I get a harder reading than if I check a 44 swc from the same pot.
A 30 cal boolit is #7 , wile the swc is #5. I cast them at the same sitting and repeated the test about 10 times. any ideas??

Buck,

Felix nailed it for ya.

My mix throws 30 calibers anywhere from 25 to 35 BHN water dropped, and 45 calibers from 20- 24 BHN. Same mix. Same temps. Same casting rate. Same, same, same.

It's not only the speed of the quench, but the speed of the cool down that makes hardness. So smaller diameters cool faster and get harder. At least for me.

[buck1]

Thanks everybody!!
These are rcbs165 sil and saeco 439. I had every thing up to full temp and air cooled them( but under a high speed fan ,witch most likely added to the cooling problim.)
The alloy is some large lead containers for some sort of medical radioactive stuff?? + 2% tin.
It casts good with good fill out, but has some silvery clinging nature about it. I can get it dirt cheep and have vishions of almost free 44 mag alloy for life.
If it works out anyway. I havent fired a shot of it yet, just tested for hardness and didnt know what to think.I will let it age and re test. Again thanks guys!!!!!.....Buck