Yes & the 30BR would have even more internal barrel length than the 308, but slower anyway. The 1/2" matters less than the additional powder the 30-06 provides. It is true that the lighter the bullet, the smaller the difference, but there is a difference. Even with the 150, the difference is close to 100 quite often. The 180 gr. will show 150fps diff. & sometimes more, especially if you have a long 180 like the Accubond or TSX that robs the 308 case more in a short action. We might as well be accurate here, I love the 308 & this winter I will probably shoot my 700VS even more than my AR, but my 06's will outrun it.
Yes, I have that Speer Manual that some want to cling to, sometimes we can have a slow barrel, sloppy chamber, loading to slightly different pressures, alot of things can determine velocity. BUT I HAVE A BIG STACK OF MANUALS & ALL of the others show the 30-06 to be faster, in a couple of cases the 30-06 shows to be very optimistic compared to the 308, it would be unfair & flat wrong to state those 2 as gospel too!!!
The 308 has it own advantages to offer, but to say it is faster or even as fast is just not the case.