Hi Guys,
Lately I have rebarrelled a few No4 7.62 conversions with unused but old target rifle barrels. They were made for the O-marks and there are some floating around rifle clubs for cheap, so they make a good blank for a No4. The threads are miles off and the chamber length doesn't work, so it's basically a full new chamber and thread proposition....Anyway, I have not been hitting the correct CHS off measurements, and found the reason to be that where I was measuring off the receiver face to the bolt face was a bit burred or dinged once and another time the receiver face had a little recess from the old barrel crushing it a bit.
So in order to be able to in future accurately face the receivers before measuring for the tennnon length and headspace/chamber length I made this little fella. It is one of the fixtures outlined in John Hinnant's great book: The Complete Illustrated Guide to Precision Rifle Barrel Fitting. For what it's worth, the mandrel through the body is a very close fit, it runs true and locks up nicely with the threads, I think it will do the trick nicely.
I will use it pretty soon and let you know how it goes.![]()