Rotometals superhard

GSPguy

Member
I bought some of the super hard alloy to mix with with some pure lead. I have never used this before so I was curious about it’s hardness so I got out the Lee tester and to my surprise it checked pretty soft. I don’t remember the conversion on the dot size but it measured .060. Can this be correct?
 

Bret4207

At the casting bench in the sky. RIP Bret.
Looking at that link from Glen I'd aim for something around 13-14bhn. Thats about what good old type WW would get you and that worked for 90% of common stuff. If you see the need for a harder alloy it's not hard at all to juice it some, or water drop/heat treat, if (and only IF) you see an actual need for a higher Bhn. Bhn alone will not solve any issues with poor fit, incompatible powders, fouled barrels, etc.
 

GSPguy

Member
Will they harden up with time? I am really thinking about my 1 pound ingots. When I smelt a batch of unknown alloy can I get an accurate reading on them after a given amount of time?
 

Brad

Benevolent Overlord and site owner
Staff member
Not really. When I pour ingots the first ones harden pretty quick due to cold moulds. The next ones harden far slower as the mould is not very hot. Could be a difference of 3 plus minutes.

Ingot hardness really tells us very little.
 

Winelover

North Central Arkansas
Alternate to Superhard/Pure mix............is one part of Roto's Lino to three parts of pure lead. Resulting BHN is 14-15 in three weeks. As tested on LBT hardness tester.
 

Bret4207

At the casting bench in the sky. RIP Bret.
What exactly are you aiming for? Are you trying to bring straight lead up to a usable point or are you trying to hit a specific Bhn #?
 

GSPguy

Member
I picked up about 700 pounds of pure lead and will be making a few different hardnesses. Doing the math is no issue. I was just curious how hard, super hard was and thought I would check it and was surprised when it checked at about 15.
 

Bret4207

At the casting bench in the sky. RIP Bret.
Well even the Rotometals site says they offer no Bhn because even they can't test it to get a Bhn. It's 30% Sb. If you know you have pure lead, like you said the math isn't that hard. You will probably want some tin and other elements in there. Ian, Fiver and some others can give you good advice there.
 

Ian

Notorious member
30% Sb/70%Pb doesn't squish with a Brinnel tester in a way that is meaningful to bullet casting. Use it to bring your Sb % up to about three or four, toss in a half percent tin for kicks and be happy. For over 2K fps or 45 KPSI you can water-quench it and/or up the tin % to just below the Sb %. Half #2 alloy (2.5/2.5) is an extremely useful alloy for rifle bullets.
 

Bret4207

At the casting bench in the sky. RIP Bret.
There ya go, one handy, dandy recipe all laid out. Is this place great or what?!!!!
 

CWLONGSHOT

Well-Known Member
Im revisiting this exact. Was gifted some super hard to season my soft RF ALLOY. SO probably enough tin already. But Im thinking 1/4 for about 12ish bhn bullets.
Sound about right?

cw
 

hrpenley

Active Member
25% will give you a bhn of around 14, back off a bit to get to 12. try about .15lb/lb lead should be closer to what you want. assuming pure lead around 8. guess you did say RF alloy, I can run the alloy cac if you let me know what you starting with.
 
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popper

Well-Known Member
SH is suposedly 36bhn ( annealed Cu is 30) but very hard to measure. I mix it with their antimony (3-5% Sb) and then cut with pure for ~50/50 (2.5/2.5). Add pure for pistol - soft.