Relationship between sizing and hardness

[Steven66]

I was wondering if anyone has experimented with varying sizing and hardness? If so, is there any correlation, for example: '0.001" oversize (over groove diameter) works best with harder/softer alloy' ?

I realize that there are many ways these variables could play out; just wondered if there was an observable tendency, even if it's limited to a specific caliber and velocity range.

[tazman]

In my experience, which I will admit is limited in this particular question, as long as the boolit is large enough to seal the throat, chamber, and barrel, the size is large enough regardless of hardness. Whether the boolit is hard enough to survive the pressures of the cartridge in which it is used is a different question.
Sometimes a soft alloy will slump under the pressures of a high pressure cartridge causing inaccuracies. Sometimes a soft alloy will slide on the rifling, allowing hot gasses to blow past the boolit causing leading. If the alloy is hard enough, none of these bad things will happen.
A lot also depends on the lube you use as well. Insufficient lube or incorrect lube will cause leading in different areas of the barrel depending on how soon it is failing.
This is just a general statement. Much more detailed information on each topic is available on this site.

[omgb]

I defer to Veral Smith of LBT fame. He indicates that a good lead/tin alloy like Lyman #2 sized .002-.003 over bore size with a good gascheck and of course, LBT blue will help you get jacked bullet accuracy and velocity out of cast bullets.

[Yodogsandman]

In my experience, which I will admit is limited in this particular question, as long as the boolit is large enough to seal the throat, chamber, and barrel, the size is large enough regardless of hardness. Whether the boolit is hard enough to survive the pressures of the cartridge in which it is used is a different question.
Sometimes a soft alloy will slump under the pressures of a high pressure cartridge causing inaccuracies. Sometimes a soft alloy will slide on the rifling, allowing hot gasses to blow past the boolit causing leading. If the alloy is hard enough, none of these bad things will happen.
A lot also depends on the lube you use as well. Insufficient lube or incorrect lube will cause leading in different areas of the barrel depending on how soon it is failing.
This is just a general statement. Much more detailed information on each topic is available on this site.

I agree with tazman.

[Steven66]

Thank you. I've been going through the forum gradually (there is an awful lot of information in it!), got Veral's book and am reading it it as well as Cast Bullets for Beginners and Experts 3rd edition. I'm going to order an LBT mold as soon as I slug the barrel.