Well, even with barrels of equal length, the real difference between the 30.06 and the 300 H&H depends on bullet-weight.

With the 150gn, 165gn & 180gn slugs, there's little gain with a 300 Holland over the newer line-up of "high energy"/"light magnum"-type 30.06 loads available on the market today.

However, if you're loading .308 bullets weighing 200gns, 210gns, 220gns and on up, that's where the larger capacity case and, especially for seating purposes, the longer neck of the 300 H&H give it a very useful velocity advantage over a 30.06 trying to throw the same slugs.

In other words, if all you're going to shoot are the 180gn or lighter .308 bullets, stick with the 30.06. That's why, except for several boxes of Federal's 300 H&H 180gn Nosler load I have around here, all other loads (my handloads) are 200gns or above.

I've tested out both the heavy hunting bullets as well as the 200gn Sierra Match Kings, and this "Super .30" is accurate with all of them.