K date Barrel Lug Marking Identify help
 

Can you help with identifying this mark under my K date barrel?

The mark is an 8.83 bore guage. This is the bore measurement from land to land in this particular barrel.

I meant on the lug, where they can be sometimes marked b90. Please let me know your thoughts, I can make out a 0 and a line

These are normal quality control / factory inspection markings and can be found all over the pistols in many shapes and sizes. They were applied just to identify the line / worker / quality checker and were part of the internal process.

Could it be an O/37 stamp? I'm guessing the right side of your receiver is stamped O/37 O/37.