diameter of cast bullet varies

[SKSer]

Hey guys I just started casting bullets for 7.62x39 and the mold I got is supposed to make a bullet with a diameter of .312, when I measure where the cast lines are it is .312 but when I measure the other way its only .309 this is the mold I purchased. It is designed for this round:

http://www.midwayusa.com/viewProduct/?productNumber=752956

it is brand new, I just cast my first 30 or so rounds and took a measurement. The guy at the gunstore told me I should be able to use this right out of the mold without sizing. Will this size variation be a problem?

[762cavalier]

Well 155 is a little heavy for x39 but should work sounds like you've got an out of spec mould. contact Lee see what they have to say.

[gunboat]

Well, it ain't round and generally speaking the small side is too small for your bore. Usually cast bullets are run through a sizer to make them round, the right diameter and to lube them. Your bore generally likes cast bullets of 311 to 313. Running those bullets through a sizer would result in a usable 308 bullet which is generally too small for even a regular 30 bore.
You need to slug your bore to see what the actual diameter is -- lands and grooves --
Your gunshop is right, you can shoot them, but you need to lube them and you might not hit the paper.
I would return the mould as unsatisfactory.
my ha-penny

[mif_slim]

could be the alloy mix too. If memory is correct, more the lead or pure lead more it shrinks while tin/lead usually stays the same size or something. But, if your bullet is "oval" you should contact Lee and have them ship you a new one. My 40SW 175gr mold has held up its end of the bargain and I load them right out of the mold.

[SKSer]

thanks for the responses guys, im going to call lee today to see whats going on or to see if they need to replace it.