H&G mold question

[Mach_Cat]

I have a 51bb h&g 8 cavity I believe 38/357 mold.
Looking at it it looks like the it would cast the base a of the boolit with a small chamfer.
The boolits I have been shooting are flat all the way across the bottom.
Why is this mold chamfering the bottom? Is this for a gas check?

[ssnow]

The "bb" you mention stands for "Bevel Base". The other option is "Plain Base" which is the flat base you are accustomed to. The bevel is designed as a seating aid, to help the bullet seat squarely without shaving lead as easily as a plain base might, during the loading process. Performance wise, it's pretty much a wash.......usually :)

For the home caster, those using a Lyman or RCBS type sizer often prefer a plain base bullet, as the bevel can fill up with lube while using those types of sizers. Those using a Star or Ballisti-Cast sizer are usually sizing nose down, and it's no problem for those types of sizers.