Dear Geno,
Thank You for the wonderful photos
You are right. The gauge 72/68 means a plug with giameter 0.400.
But it is very important to understand the next things:
1-st - it is the largest of the plugs that would fit in the bore.
2-nd - increment between plugs is 0.010 inc
3-rd - the measurement had been done before the rifling (!)
So, the 72/68 means that diameter was approx. from 10.16 (0.400) to 10.42 (0.410) before rifling.
I am sure this barrel is for 10.75 Grundig.
I wiil try to add an image of 10.75x65R Grundig cartridge a little later
I have send a P.M. for You. Have You received it?
