NPM Numbering System Question

I am restoring a 4.6 mil NPM and was wondering about the numbering on the bolt, slide and trigger housing. Should the numbers all be the same? a N-12 bolt, N12 trigger housing and a N12 slide? or were they mixed? I have a N9 trigger housing, a N12 bolt and a N14 slide?
Thanks
Bill

4.6 would be QHMC. If you have a 4.06 I would think all sounds about right.
For sure I will be corrected..

A 4.6 range could be Rock-Ola or QHMC. 4.06 would have been assigned to Underwood.

sorry all it is a 4.23 mil
Bill

The numbers won't match.