Explain this to me please....Rotometals hardball alloy

[Ridgerunner665]

It water quenches to 30 BHN!!!

It is a 2-6-92 alloy, it casts some very nice looking boolits, it drops at the right weight (much like Lyman #2)....its good stuff!

But what is it that allows it to be quenched to 30 BHN?

These boolits were tested by somebody that knows how to use the tester (an LBT tester)...you all know him, he is a member here...but I'll leave it at that.

I cast some Ranch Dog TLC-460-350's over the weekend and fired one of them point blank into frozen ground...very frozen ground...2,050 fps, it weighed 231 grains when it came back out of the ground (346 grains was the original weight of the bullet without a gas check or lube)

A Beartooth 405 LFN/GC fired into the same frozen ground at 1,900 fps weighed 270 grains when it came out...

Its not a "brittle" 30 BHN...my first thought was maybe Rotometals messed up and sent me some Super Hard alloy...but those would be brittle I think.


Any ideas?

[Ranch Dog]

Hope you don't mind Ridge... but I will add the photo of the tester in use on your bullets. I operate the LBT Tester according to the instructions, including bullet prep, plus three samples per bullet. These bullets are hard!

[Ridgerunner665]

I don't mind at all Michael...

I'm just trying to figure this out...you know how it is...inquiring minds want to know, LOL.

[RobS]

Alloy temp as a lot to do with water quenching hardness. Iron molds that I cast at lower temps with end up producing softer boolits than let's say some of my aluminum molds which require warmer alloy to keep the mold temp up for fill out. What temp was the alloy at when you cast those RD's.

[Ridgerunner665]

Exact temp...unknown.

Pot setting (Lee Pro 4-20)...8

[RobS]

Well, I cant say as to your setting since Lee rheostats are all a bit different in regards to regulating temps. However 8 is up there on some of the Lee pots I've worked with. When I cast at 800 degrees straight WW can be up as high as 25-27ish BHN. If the boolits are too hard you can anneal them back down in an oven.

[Ridgerunner665]

The hardness isn't really a problem (maybe even a blessing...)

It was just unexpected...I was expecting 18-19 BHN and when Michael told me 30 I didn't quite know what to think, LOL.

Its a 45-70...no expansion necessary, but I don't want them brittle either...so it seems I'm good to go, no matter how fast I choose to push them.

But...for the sake of knowing...explain that "annealing down" process to me if you would please.

[Tazman1602]

FYI Ridgerunner setting 8 on my Lee 4-20 pot is way too hot. When I get it up to temp it only needs between 4-5 to maintain around 690-725 degrees.

I'm not saying YOUR pot will do that, just a thermometer observation I made with mine that cured all kinds of ills for me.

30 BHN now that is hard!

[Ridgerunner665]

FYI Ridgerunner setting 8 on my Lee 4-20 pot is way too hot. When I get it up to temp it only needs between 4-5 to maintain around 690-725 degrees.

I'm not saying YOUR pot will do that, just a thermometer observation I made with mine that cured all kinds of ills for me.

30 BHN now that is hard!

I'll get a thermometer one of these days...

[RobS]

Annealing is simply softening them by heating them up in the oven. Let's say 325 degrees for an hour and left in there to cool may pull them back down to 13 BHN or so depending on your oven. Less oven heat will yield less annealing so harder bullets and more oven heat goes the other direction and softer bullets are the outcome. WW alloy will get as soft as 10-11 BHN annealed at 350 degrees for an hour and left in to cool to room temp (in my small convection toaster oven) and remains there where as my air cooled can range from 13 to even upper 16 BHN this last go aroud when I was casting in the garage at 17 or 18 degrees F.

[Ridgerunner665]

Annealing is simply softening them by heating them up in the oven. Let's say 325 degrees for an hour and left in there to cool may pull them back down to 13 BHN or so depending on your oven. Less oven heat will yield less annealing so harder bullets and more oven heat goes the other direction and softer bullets are the outcome. WW alloy will get as soft as 10-11 BHN annealed at 350 degrees for an hour and left in to cool to room temp (in my small convection toaster oven) and remains there where as my air cooled can range from 13 to even upper 16 BHN this last go aroud when I was casting in the garage at 17 or 18 degrees F.

Thank You for the info...

[Ranch Dog]

Ridge

I've got a database of every casting session I've done. I record quite a bit of info. For instance, pot index settings against thermometer temperatures taken at 15 minute intervals. I know, I'm weird. This information has come from two Lee Pro 4-20 pots. I use this info mainly to help repeat performance.

A search of an "8" index on the pot has produced an average of 773° on 27 temperature interval checks.

[RobS]

A person can also use the oven to speed the age hardening process up as well. Where as it may take up to 2 weeks or more to age harden an alloy a person can put their bullets in an oven at 200 degrees and the aging process can be reduced concederably.

I've age hardened bullet to full hardness or near it with this process:

3 hours or so after casting put boolits in oven for an hour at 200 degrees and leave them in to cool.

7-8 hours later, another round of 200 degrees as above.

Not hard at all and I usually do the first exposure just before bed and then again as I wake up in the AM. If I want to anneal them then I do it after the second exposure. Cool ehhh!

[Ridgerunner665]

Ridge

I've got a database of every casting session I've done. I record quite a bit of info. For instance, pot index settings against thermometer temperatures taken at 15 minute intervals. I know, I'm weird. This information has come from two Lee Pro 4-20 pots. I use this info mainly to help repeat performance.

A search of an "8" index on the pot has produced an average of 773° on 27 temperature interval checks.

Not weird at all...its a good idea.


773 degrees...that don't seem too outrageously hot, but then again...I am new at this, LOL.

It made some purdy boolits....

[RobS]

Ridge

I've got a database of every casting session I've done. I record quite a bit of info. For instance, pot index settings against thermometer temperatures taken at 15 minute intervals. I know, I'm weird. This information has come from two Lee Pro 4-20 pots. I use this info mainly to help repeat performance.

A search of an "8" index on the pot has produced an average of 773° on 27 temperature interval checks.

That's good info, but if your ambient temp changes so does the cycling of the rheostat as it sets in the housing unit. I.e. an 8 setting today at 30 degrees will cycle more than an 8 setting tomorrow at 17 degrees. When the ambient temp is cooler in the housing unit the rheostat stays in contact longer producing longer episodes of current to the pot.

[Ridgerunner665]

Age hardening...

I guess it should be noted that those boolits Michael tested were 2 weeks old...(+ or - a day or two)

[RobS]

Two weeks for all practical purposes is going to run you about right for age hardening, acutally oven heat treated (heating bullets up and then quenching them in water) or water quenching directly from the mold seems to harden quicker (a week or so).

[Ridgerunner665]

I dropped these from the mold into a 5 gallon bucket of water...

[RobS]

Well, considering you're probably casting at around 775 + degrees and in conjunction the higher antimony content vs WW alloy then your results would be linear with my results of WW alloy (2-3% antimony) at 800 degrees yielding 25-27BHN. This is all speculative on your pot having alloy at suggest temps though.

[Ridgerunner665]

Well, considering you're probably casting at around 775 + degrees and in conjunction the higher antimony content vs WW alloy then your results would be linear with my results of WW alloy (2-3% antimony) at 800 degrees yielding 25-27BHN. This is all speculative on your pot having alloy at suggest temps though.

Yep...its starting to add up now.

But it threw me plumb off the horse at first....LOL.