I think Mauser possibly used 28" test barrels (~71 centimeters), Brits certainly used 30" sometimes more, not that it makes a great deal of difference.
Perhaps kuduae will pop in and give a definitive answer?

At any rate my 1936 Rigby Mauser has an action that is Mauser serial number #1123 from 1899 production so I'm not inclined to experiment with trying to attain the "advertised" 3000'/sec.
Shoots "to the sights" at ~2775'-2800'/sec with 140 grain Nosler Partition's. (or close enough with the iron sights and my old eyes)
- Mike