My lack of knowledge regarding cast bullet accuracy has been well established by now, so there’s little chance of embarrassing myself and further, so I’ll ask another.
This question regards “sizing” the base of the bullet. This is typically done in a lube sizer (Lyman 450, SAECO, RCBS), but often times casters will size bullets through “push through” sizers such as Lee or NOE. Which ever way you choose, the end result is meant to “size the base of the bullet. About a month ago I broke this into a two step process. I’m now adding the check & sizing with the push through Lee then adding the lube with an “as Lee already sized” diameter die in my Lyman.
In the past couple, three years I’ve seen post where casters refer to the base sizing diameter in the .0001 of an inch. Most commonly to the .0005”. Identifying the base measurement to the tenth of a thou is also seen in the equipment list for the BR Nationals.
When first pound cast in October 2021, my Savage’s freebore measured .3089/.3092. I could see skuffing on the front drive band when sized to a lube die of .308 so I stuck with a .308 die. When I recently switched to a Lee .309 push through die it resulted in a .3098 base and that’s where it’s at now.
So the question is, how critical is the fit between the freebore and the sized bullet base? Or said a little bit different, Is the fit of the sized bullet to the freebore dimension important to cast accuracy. Thanks, Bill C.
