7.7x62r

ever hear of this caliber??
saw a German double rifle chambered for it

Barnes lists a 7.7 X 60, if that is it. It's an old cartridge and appears to be based on the Mauser "A" base case. BP cartridge and obsolete for decades....and maybe even a century, which makes it my kind of cartridge! It is evident you don't have the rifle in hand but a chamber cast would tell you and if it is on the "A" base, 43 Mauser brass is available and it could be made.

Actually,you can tell if it is on a "A"base(MB)case without a chambercast. If it is, the rimrecess will be deeper than normal and the chamber would measure around .518-.520" in front of the rimrecess( which it self usually measures around .595").If someone else owns the rifle, they will be more likely to let you measure the chamber(dial caliper works, with or without hole gage)than take it to make a chambercast.Note, this doesn't ID case length. FWIW you can make satisfactory cases from 45-90 cases.
Mike

I didn't get that very clear, did I....again...lol. I meant the chamber cast could tell you whether or not it was the 7.7 X 60, not if it was on the A base.

However...as is usual I learned something.

Vic,
The point being that if it wasn't on an "A"base case, it wouldn't be 7.7x60R, and since someone else owned it, it would be difficult to make a chambercast.On the other hand, it wouldn't be hard to get the owner to allow measuring the head dia., and rimrecess depth. This could only exclude 7.7x60R, not show it is the caliber.
After further reflection and no additional information,I have come to the opinion that the rifle is likely chambered for a nominal 8mm cartridge. 7.7mm is often the bore diameter marked for 8mm barrels,along with 7.8 and sometimes 7.6mm.I believe the marking reported in the original posting is not the name of the cartridge, but the proof mark, showing bore(not groove or bullet)diameter and case length. If this is the case, it is likely chambered for a cartridge known as 8x62R Vierordt no 102. This cartridge is one of the several 8mm cartridges based on the British 360 Express case, which was adopted by the Germans and used for such cartridges as 8x57R/360 and 9.3x72R.Measurment of the chamber in the casehead area could also disprove my theory and exclude the 8x62R Vierordt.If I am correct, the diameter should be around .429" + a couple thousanths.
Mike