The action appears to be an updated 71/86, which originally (back in 1871) was a Model 71 designed and built by Peter Mauser and chambered for the 11 mm Mauser (.43 Mauser). IT later became the Model 71/76, also in 11mm Mauser, then the Model 71/86 or M71/84. This later version had a .446" groove diameter, rather than the original .457" groove diameter. The both had the .437" bore diameter - yes, it's wierd.

I did not know this action was used later than the 11mm Mausers, and for the 7.8mmX57 mm case. That is quite intersting.

Does this mean the 7.8x57 was originally a Black powder round? or were the 71/86's 'converted' or did they preceed the M88 and actually shoot the same .318" ammo with early smokeless powders?

I guess have questions too.

Yes, the extractor is easily lost from a removed bolt.

Tom - does this rifle have 2 bolt lugs or just one? I see what looks like a lug on the top of the closed bolt, but that is merely a guide to run in a slot when opened, I believe. a single bolt lug was complained about, in the 11mm mausers due to bolt cant on firing and susupected reduction in accuracy as a result. That's just one speculation/observation they made.

My own M71/76 has a virtually smooth, round bolt, except for the long bolt handle attachment, which is it's only lug. Other than the small lug/like guide shown in your picture, are they any other 'lugs' on the bolt's surface?