I have a yellow box of spire point 180 grain bullets that say they are .3085 diameter made by Vernen D Speer.
.3085 - 180 - 6 - SP is what is marked on the side of the box.
They have a dimple on the base of the bullet. Are these hot-cors or what are they? They are in very good condition and so is the box.

Speer started making the hot-core bullets in the late 40's
in the speer #6 manuel the loads listed for this is a 308wcf using
Hi-Vel #2 powder. That will take some of us way back. I checked some of my 300 savage loads and a refrence from Ken Waters was .3085 Another refrence note was that they could be used in the .307 winchester which calls for a .309 bullet dia.
Dave

Speer used to size all of their .308 bullets to .3085". The practice of sizing bullet to slightly larger than nominal bore diameter (which varies more than you might think between rifles) is an old one that several companies have practiced. It means nothing in terms of accuracy/pressure, etc.

Speer also used to size their 6.5mm bullets to .263" rather than the .264" which most other companies use. I've used a lot of those .263" Speer bullets and couldn't tell the difference in those which were listed as .264". They all get fatter when you suddenly apply 60,000 psi to their asses.