7.62NATO
I am thinking you might be good....
it did meet some resistance when inserting it. The ram rod sits VERY close to its corresponding channel, but you can see that there is an infinitesimal gap there, but nonetheless, a gap.
This statement converns me just a little bit... Remove the ram rod and try the test again. If the bill just barely gets in there.... think about this - if you put upward pressure on the forearm of the stock would it push on the barrel? If it does you might move POI - but your point is well taken - a bit of light sanding in the channel on the nose of the forearm of the stock would take that away.
The thing you want is when you are shooting and applying upward pressure on the forearm it should not touch the barrel.
Hope all works out well...