I have four 98 sporters built on Oberndorf military actions made for Portugal in the '30's. The calibers are 6.5X.308 (.260 Remington), .308 and .358, plus a wildcat .400/.284. They, plus my little 7X57 featherweight built on a G33/40, are my favorites.

For a longer cartridge, I would have to go with the Argentine 1909, especially with their beautiful hinged floor plates and long cocking pieces.

I bought all these actions decades ago, and I have no real feel for current prices, although I have the feeling that the G33/40 prices are out the roof. At one point Flaig's in Millvale, PA, offered the Portuguese Oberndorf Mauser actions for around $35.00 as I recall. To put this in perspective, at the same time for $35.00 you could buy either a 1903 Springfield, a Walther P-38 or a Mauser HsC from Interarms in Alexandria, VA. (I bought all three.)