SPORTERIZING MILITARY RIFLES views and tho
If you really want unique, how about the 9.3x57mm? Shoots .366 caliber bullets. Very popular in Europe & Africa, but almost unknwown here.
To answer your quetion, t hey do remove the barrel in order to re-bore it. Cost for the total job is $185.00. Advantage is that it's already inletted and fits the stock and lis entirely original except for the rebore. And I don't know anyone who will rebarrel and re-fit for less than that.
I have a couple of mausers and have contempalted several re-bore options including the 8x57, 8x57 AI, .338x57 Improved (aka .338 DGS) , 9x57 and 9.3x57.
There's a guy in North Dakota, Norman Johnson, who does this kind of work and really seems to know whtat it's about. Speaking of the 9x57, one of the popular re-bores with mausers is to use a .358 bore and to use a .358 expander in the reloading dies so that you can shoot American .358 cal bullets rather than European .355's. He said he could do a .358 x 57 mm with an AI (40 degree) shoulder. Compare the 9x57 with the .35 Whelen. The Whelen is a much longer case, but becuase so much of it is the long neck, the lengh of the 57 mm case from the case head to the shoulder is almost as long as the 35 Whelen. IMHO a 358 x 57 AI would probably be as potent as a factory loaded .35 Whelen. Also, Becuase the case to shoulder length of the 57 mm case is slightly less than the 30-06, you can die form improved cases from the longer 30-06 cases without the need for fire forming. That's what's really cool, at least to me. Would probably have to have a custom trim die made, but would pay for itself very quickly because you wouldn't need to fire form.
(Note: you can do the same thing with the .250 Savage AI using .243 Winchester cases. They die form right into .250 AI cases.)
I've also seen a 338 x 57 Improved, called the .338 DGS, that got 2600 fps with a 225 grain bullet. You could also die form this one from 30-06/270 cases in lieu of fire forming. What with the lighter weight .338 bullets (i.e. 160, 175, 185 Barnes X bullets, 180 & 200 grain Nosler Ballistic Tips and 210 Partitions, as well as the 225's and 250's) the .338x57 might be a better, more flexible choice. This would probably duplicate the .338-06. An interesting idea to contemplate.
The purpose of the 8x57 (and the 8x57 AI) is to use cheap surplus ammo. Also, the newly bored barrel is just like a brand new barrel. Some of the old miliatary barrels were grossly over sized and had really long throats. A more uniform bore and a shorter throat would produce better ballistics and better accuracy with the 8x57. The selection of 8mm bullets is really very good as of late. Hornady just added a 195 grain spire point and nosler a 180 grain ballistic tip and 200 grain partition.
The 9.3x57 is an old round that shoots .366 caliber bullets. Very popular in Africa and Europe, but almost unknown here. Swift, Barnes, Nosler & Speer make .366 Cal. bullets in 250, 270 and 286, 300 grain weights. But they are very expensive and not very flexible. Would be a fun round, but since it's only .008 larger than the .358 and does not have as much of a variety of bullets, the .358 x 57 would probably be best.
You could take a miliatary surplus mauser, re-bore for $185.00 and use a Scout Scope and you could have a neat .338, .35 , or .36 ca rifle for about $225.00. With the extended eye relief scope, you don't have to bend the bolt and you can still use stripper clips.