The mold is a 405gr rnfp Lee bullet mold. The pot is a 20lbs Lee bottom pour. Coww for lead source. Brass is starline, sized and belled with Lee 3 die set. Lubed with Lee alox thinned with mineral spirits.
The problem is about half of the bullets dropped from the mold is slightly undersized. Enough that once loaded, I could press the bullets in with my thumb. Also 75% had rounded edges to the lube grooves.
My question is, is this a heat problem with the mold, or lead? Possibly a problem with my lead? I was casting outside in about 40 degree sunny day.
I have cast 32 and 9mm and never had this problem before, with maybe 5% to 10% rejects. But it was in warmer temperatures as well.
Any help would be appreciated.
The problem is about half of the bullets dropped from the mold is slightly undersized. Enough that once loaded, I could press the bullets in with my thumb. Also 75% had rounded edges to the lube grooves.
My question is, is this a heat problem with the mold, or lead? Possibly a problem with my lead? I was casting outside in about 40 degree sunny day.
I have cast 32 and 9mm and never had this problem before, with maybe 5% to 10% rejects. But it was in warmer temperatures as well.
Any help would be appreciated.