Who would be good to checker the top of front ring on Mauser like the Type A?

I believe it is 30-40 LPI on the Type A, still verifying the LPI.

It will be a 1935 Chilian if that make a difference as far as how hard the front ring is.

The front ring only will be surface ground, just enough to remove all the crest & lettering for checkering.

Allen

You will have to send it to an engraver; originals were rolled on and I have never found anyone with a roll (which would be expensive to make and the receiver would have to be annealed for it to work). I would have one made if I thought I could make any money with it. An engraver with carbide tools could do it.