Quick Load, yes I know it is a shacky piece of software, gives the case capacity of a 30-06 at 68 grains and with a 3.45 OAL 62 gr. of powder capacity. The Gibbs, using the same criteria, has 72 and 65.4 respectively. That is a 3.5 gr. burn capacity +/- difference. By my math that is about 5.5% of useable or total capacity increase with a 3.45 in. OAl. Real results should be about 100-125 fps. +/- assuming you load all to the same pressure level.
My presumption on the old data is that the hand loaders pushed up to 65 K (or more) and the factory loads were at 50K so you were comparing apples and grapefruit and selling the grapefruit.
Remember YMMV.
