7.62 No4 MKI conversion question

[Lee Enfield]

As I've heard it, the bolts and bodies were magnafluxed to check for cracks (same process used for cylinder heads etc) then hardness tested. If they passed those two, then the conversion was done, proof fired and if that was succesful, then the maple leaf mark and the conversion number went on. If one looks underneath the bodies near the front guard screw boss, the 'punch' marks left by the Brinell hardness tester can be seen.
snip....

They're not actually Brinell impressions (too small). DPN or HRC of some type.

Hardness impressions are also on both bolt lugs, and sometimes on the boltheads. Also noticed on the striker cam on the bolt body, and the sear surface of the striker.

Sometimes the bolts are the originals which came with the action. Sometimes they are new unserialed replacement LB bolts with just the conversion number stamped on the bolt arm.

The Parker Hale markings could have been applied if the gun was gunsmithed/accurized/bedded at some point by P-H.

Have/had one that was "Fulton's of Bisley" marked on the receiver ring....