What alloy to use?

[ronniet]

I am new to casting but I have the pot, lead, molds, most all the equipment except right now the correct sizing die and knowledge of the alloy to use. I have no Lubesizer only used the Lee dies.
Most all my lead is from old plumbing and wheel weights, molded into ingots already.
I don't know the content or hardness.
I have a few of the Lee dies that I have sized Jacketed bullets for my 351 an 401WSLs. But I want to shoot 250-270gr. cast boolits w/GC for a 375 Nitro Express @ about 2200fps.
So I need to know if this will work if so what hardness or alloy, and where can I get a die to size for .375 Lee does not make one.

Or am I going to have to use jacketed bullets?

[RU shooter]

I would try your soft and WW alloy and water quench from mould and give it a go

[robg]

Make sure they are the right size for the bore ,add a bit of tin ,use gas checks start low and work up .might not be that accurate if you push them too fast.