I have been a member several years and have been collecting other milsurps / C&Rs for 25 + years. a little over 5 years ago I changed direction of my collecting to Single-shot rifles and have assembled quite a few nice pieces. I have learned much here and by the ref book by Marcot and Laymon. Now I need some help. I aquired a custom Martini, looks like a German or maybe Swiss build. Quite a nice rifle but I am curious as to the builder, and of course the cal. the seller just stated it was 40-77 with nno reason for that assumption. I will attach pic in my next thread. Any help will be appreciated.

German proof marks:
     The crown-over-G is the mark for rifled bbls.
     The crown-over-R is a re-proof mark
     The crown-over-U is a "view" (inspection) mark

These were used from 1891 to 1939, and are consistent with what looks to be proof date marks 2-08 and 9-08. ( The re-proof would be applied if, e.g., something about the chamber was changed.)  Looks to me like the "8 8" is a maker's serial number, two "8"s  struck with a broken stamp.

In the 2nd photo, the edge of what looks like a Swiss rear sight is showing.?

I haven't seen an action like this.  A chamber cast would be enlightening.  I find that sulfur is the easiest, cheapest, and most useful material to use for casts.

CHRIS
RGChristensen

        Sulfur makes excellent chamber casts.    Possibly Cerrosafe alloy is better if you want "that last thousandth of an inch", but sulfur is cheap, readily available, and easy to use.     I put a piece of paper towel ahead of the chamber and fasten the barrel in a vertical position.   Melt the sulfur gently in some convenient container, which can be a cut-off beer can (ask your neighbor to save one for you).    Swirl it over a stove burner or torch until most of it is melted. If some un-melted material remains, then it is NOT too hot. It should be a limpid, yellow liquid. If you are getting it too hot, it will show a reddish color. (this color is due to an allotropic change in molecular structure -- it is not "burned" and will revert back to the yellow form on standing at room temperature.)  Take care that it doesn't catch fire, as sulfur dioxide is nasty-smelling stuff. Pour it in until the chamber is nearly full.   Accidental overflows can be picked out of crevices, etc, whilst Cerrosafe will require heating up the whole gun to melt it away.   Then push out the sulfur cast with a rod.    If you drop it, it will break, but it will stand considerable measuring with calipers or micrometer.

CHRIS
RGChristensen

Not an expert at all.  Just some random thoughts: 

1.  My guess (fwiw) is that the 67,49 might refer to some sort of proofhouse log book or record.

2.  Slugging the barrel and looking & measuring carefully both the lands & grooves will tell you a lot.  Look with a big magnifying glass.  Please keep us informed.

3.  Measure the twist.  It probably will not be fast, but it will be metric.  You will need to convert from inches per turn to cm per turn.  Please keep us informed.

4.  Guys experienced in chamber casting use children's modeling clay to seal cracks and to make a little base dam for the cerrosafe casting.

5.  To me it looks like a stalking rifle built in Germany on a Swiss-designed or influenced Martini action.

6.  Is Biggi still around?  Ask her.