.312 160 Gr. Lee -How to bump up diameter?

[squirrellnuttz]

Anybody know? I cast a bunch in straight Wheeweight metal, and they drop at .312.5 ". My bore slugs out ( after some seroious farting around) to .313.5" to .314"
So, please feel free to correct me, but if I add some tin to the mix, it may increase the diameter of the boolit when it drops out of the mould? Any idea on how much tin to try? Or maybe a temp change may help? I cast at 750 deg. F according to my RCBS pot.

[GP100man]

Search "beagle a mold" some spin a boolit with lappin compound but the more ya spin it the more the corners round .

[zuke]

Paper patch it!

[RU shooter]

Beagle it with some .002 thick metal ie: feeler gauge or alum foil or foil tape. Adding some lino/mono alloy will yield another .001 give or take.


Tim

[Bret4207]

Okay, I assume you mean your groove size is .314, not your bore. "Bumping" is the process of taking a sizing die of your desired diameter (around .315-.316 in your case) and close fitting top punch and applying pressure to the sizing handle. This will "squish" the boolit and it can only expand as large as the sizing die. Not real accurate, not real repeatable and very hard on your sizer, but it works.

[Rico1950]

Use the 3M Flue tape. I used it on the Lee .312-155-R. Went from .3125" to .314-.315".