There's so much good advice in the above posts that it may be hard (no pun intended)
to digest it all. I've been casting and reloading for 51 years. For the first 40, I agonized over the correct Lyman #2 alloy, gas checks, etc., etc. As tin and other components became very expensive and more difficult to obtain, I was forced to reluctantly try compromises and shortcuts. Now I'm into easy things that work, and cost less.
(A) I've switched to straight wheel weights, period. They are fine up to 1200 FPS or so. Beyond that, use gas checks with the same alloy.
(B) Yes, quenching makes the bullets harder, but what you gain does not come close to justifying the effort, and in almost no case is it really necessary.
(C) Your bullet lube is probably more important than the lead alloy. With modern lube recipes including an Alox equivalent, you can use otherwise poor and soft alloys up to rather high velocities, without any sign of leading. You can buy or make your own lube. Recipes are all over the place; most of them work.
(D) This I know for certain, and it is contrary to everything I "thought" I knew several years ago. Using straight wheel weight alloy and gas checks, you can drive .30 and 8mm rifle bullets in the 2600 FPS range, through a smooth and unpitted bore, without leading. And you can do this in a gas operated rifle without leading up the gas cylinder. I've done this in several of my Garands and several M-1 carbines. In the past, I had terrible luck with this. Correct bullet lubricant made all the difference.
(E) Test new methodology before deciding it won't work. There is a lot of good information on the Internet, but also a wealth of misinformation. And I realize that a lot of what I've said above is contrary to some popular thinking from some knowledgeable people. That's why I made reloading unnecessarily difficult for myself for too many years.
Summary: Use straight wheel weights, a lubricant including an Alox equivalent, and gas checks above 1200 to 1300 FPS. Don't worry about water quenching, but do it if you like to play with a pail of water. Our real worry is that socialist fanatics presently calling the shots are in the process of trying to ban the use of lead alloy wheel weights in the United States. That's why I've stockpiled a good supply. Make some friends at your local tire shop.