Re: 30-06 barrel length
Leupold you have is the scope I would put on it. Mine has a 4-12 Weaver (older USA made Micro-Trac) and it is fine to a kilo. Your upper shooting range limit is well served @ 10X.
A lot has been written about powder vs. barrel length. Pistol calibers in rifle length barrels will "burn out". 22LR rimfire stops accelerating at about 18". The Olympic guns w/ 28" barrels actually slow the bullet down. 9mm Luger 147gr Sub-sonic loads will actually stick in barrels over 10"!!! Most medium to high intensity cartridges gain velocity up to 28" - 36". I'm not knocking what you said. But hunters do not use target loads of 4895 made for M1 DCM Matches. The powders that drive the 30/06 will need all of 26" to burn and then some.
Short barrels (<22") do not utilize the slow powders we use. But in my experience the 30/06 benefits from 26". The magnums should be minimum 26". Again I say I'm not knocking on your house, don't take this as a negative.
Wanting as much data as possible I bit the bullet and bought a Pressure Trace II. It cost as much as a complete rifle, glass and all. What it shows is the peak pressure for 4350/4831 speed powders occur about 13" down the barrel. This is in a 300 WinMag and 375 Ruger. The pressure tapers off after that until the bullet exists. But the bullet is accelerating all the way out and some studies say the bullet is pushed for another 1" - 2" past the muzzle.
What I can say is the efficiency of the load is helped by a barrel of 26" length for powders 4350 and slower. The gains for faster powders will be reduced and in the range of 3031 you probably have exceeded the efficient length of barrel. But short of lead bullets loaded with Unique, 26" will help velocity in a 30/06. sean1 stated 180gr bullets and in 30/06 he's going to be using one of the 4350's or something slower, guaranteed.
The best thing about your post, kcebcj, is it gets people to think about longer barrel for their guns. Short barrels for short ranges! If you need a short barrel to turn around, fine. But most people would be better served with a longer tube!!!