I purchased a box of bullets from Black Widow and I had chambering issues. I compared notes with @1Fatman who was doing pretty much the same process, but he didn’t have any issues.
I then ran the finished round through FL die and it chambered perfectly. Suspect the hill was too wide on Black Widow projectiles. That’s the only issue that would have been fixed by the FL die. Then @1Fatman sent me a sample of his cast bullets, cast with CBE mold and those worked perfectly. No post-load FL sizing needed.
There’s also a Youtube video of some guy getting the same issue with the same projectiles.
So, buyer be ware, probably a lot cheaper and faster to buy a CBE mold to start with.
HRBC and Black Widow, as far as I know use the same molds, so bullet would be the same and FL on the finished round would be needed.
Sizing bullets will not work, because the seated part (heel) is smaller than the top part of the bullet.