Sorry again for the confusion, my original post on this thread wasn't very clear. The question was only meant to compare the 338-06 and the 338wm cartridges, and my intent is, and has always been, if I went with the 338-06, to convert my old .30-06 to a switch barrel, or if I went with the 338wm, to build a new rifle. Never any intent to convert my old .30-06 to a 338wm.
When I came to post this thread, I was still on the fence as to whether to drop $2000 on a new rifle in 338wm, or simply add a 338 A-square barrel to my 30-06 for around $500. But in the interest of avoiding the financial discussion - since I know I'll spend the money on the "right rig" regardless of the 4x multiplier - but rather wanted only to focus on the cartridges themselves.
Since then, I bought a 338wm rifle, a 338wm barrel for a 7mm rifle to be a switch rig, and a 338-06 barrel for my 30-06, so I don't have to choose.
I've done the "changing cartridge family" conversion deal before, and in certain platforms, it's not really that difficult. For Remington and Savages, spare bolts/boltheads, mag boxes, followers, etc are easy to find. For the Ruger's that I'm building upon right now, spare bolts are like hens teeth, so it's a non-starter. On the other hand, I have a set-up for one of my wife's rifles to swap between 223rem and 243win, only takes about an hour and a half, and all of the parts were available off the shelf at Midway. At the end of the day, it's not that hard to swap families, but that wasn't my goal for this set of projects.
One particular disadvantage of the 338-06, but not a show stopper, and equally if I were making 9.3x62mm brass from .30-06 brass, is that the headstamp on imported ammo has to match the chamber marking of the accompanying rifle. So I'd have to spend the money on brass with proper headstamps if I intended to take this particular rig overseas. Not a show stopper, as Norma, Nosler, and Wby all make 338-06 stamped brass, but it's still an extra hassle.
Part of my motivation for the 30-06/338 A-square switch rig is that I'll be passing that rifle - my first deer rifle - down to my son in a few years. I was basically at a crossroads where it doesn't shoot well anymore, to the point I wouldn't be proud to pass it down, and I wouldn't expect my son to be proud to receive it. I had the choice to either scrap my old rifle, or rebuild it into something my son can be proud to shoot. At the same time, my wife and I settled on a pair of Ruger stainless actions to have our own switch barrel rigs. So now my son, my wife, and I (when he's old enough) will have switch barrel rigs suitable for hunting whitetails here at home, plus an extra tube suitable for much larger game, should the rare need arise. 30-06/338-06, 7mmRM/338wm, and 300wm/458wm.
