This is an observation with a question.
I started casting my own handgun bullets in the mid to late seventys. Casting for various.45's, .38's and .357's in both autos and wheel guns.  I used wheel weights almost exclusivly and had virtually no leading and very good accuracy.  In the last 10 years or so I haven't cast any bullets.  I have had to rely on commercial cast bullets.  Most of these are bevel based machine cast bullets, and they vary in hardness from maker to maker.  It's almost impossible to find a consistant source of good redily available flat based bullets.  
(Note:  BTB bullets excepted because altho I have purchased some, I haven't been able to get them loaded and tested.)
With the commercial bullets I have used, I get poor accuracy and severe leading.  This has happened in autos and revolvers, with standard and magnum loads.  
Since I began to read forums such as Beartooth and others I have learned more about bullets than I ever knew.  I learned that bullets can be TOO hard, this will cause leading.  They can be TOO small for cylinder throats and this will cause leading and very poor accuracy.  I have also learned that my dislike for bevel based bullets is founded in fact.  Bevel based bullets are more prone to leading than flat based because the powder gasses are more likely to flow around the beveled base than they would a flat base.  
I have learned that the chamber throat diameter to barrel GROVE diameter is critical to accruacy and leading in revolvers.  And that manufacturers don't care a bit about tightning this critical dimention up.  
I have learned some about forcing cones, altho I have yet to get any concrete information about this subject.  Every one has a different opinion about this.  I would love to find a thourough test article in print.  
So having said all this I am again, with spring aproaching thinking of digging out my casting equipment.  
My question:  What is the hardness of wheel wieght lead?  
I have had good luck with this hardness, and figure I might as well go back to it.
What alloy, preferably one that is commercially available, would I ask for?  
I would like to get away from the mess of cleaning wheel weights if I can.
Please forgive my lengthy comment.
Any answers and help is greatly appreciated.
JM

It's my experience that alloy hardness has less to do with leading then bullet diameter.
I have several bevel base bullet molds that don't lead in my handguns. I use wheel weight alloy with a bit of tin for better fill out. I size all of the bullets for my 45 Colt .454. For my 45 acp/auto rim .4525. For my 38/357 I size to .360- .359- .3585.
Another difference maybe that I lapped the barrels on each of my handguns.
Hopefully this helps.
Jim

The last I knew, wheel weights were about 97.25% lead / 2.5% antimony / .25% tin and a trace of arsenic. This goes back to the 80's and the bhn of that composition when air cooled, was around 12.

I picked up some wheel weights recently but don't know their history. Bullets made from them are about the same weight and the bhn is also around 12.

As you have found, they are a very useful alloy and their lower bhn allows obturation which is key to preventing throat leading.  Bullet diameter is also key as Arkypete indicated.

It is the alloy that I use most.

John

A few ways to closely duplicate wheel weight alloy are:

Buy LAWRENCE BRAND® CHILLED SHOT which is a  2% Antimonial Lead Alloy. Add 1-2% tin for better castability if required.
 
Get  LAWRENCE BRAND®  HIGH ANTIMONY
LEAD SHOT  which is a  5-6% Antimonial Lead Alloy.
Add equal parts of lead to cut the antimony content in half. Add 1-2% tin for better castability if required.

If you can find some Linotype, which are typically single rows of letters,  mix 1 lb. of that with 3 lbs. of lead.  No need to add any more tin.

If you run across some single digit letters, they would be  monotype.  There are several formulations of monotype but let's assume it is the most common.  Mix 1 lb. of mono with 9 lbs. of lead and you will have a 12 bhn alloy. No need to add more tin.

Hopefully this helps.

Have fun!
John