Dear colleague:
could you please advice according to AISC is there an accepted gap in moment connection between Beam end plate and column flange or it should be fully contact.
are you are welding it with a full-penetration groove weld and you want to know about gap and gap tolerances...? start with AWS pre-qualified welds in D1.1.... if outside that, both the weld and welder will need to be qualified per D1.1. there are some techniques to bring it back to tolerance
Usually, the beam end plate would be expected to be in full contact with the column flange if bolted. There could be exceptions for welded connections.
For a bolted end-plate moment frame connection, 1/4" is the maximum acceptable gap that can be filled using finger shims with no reduction in bolt values.
I often use a thicker plate shim and design the connection accordingly. This permits easier installation of the beam, else, it's very difficult to slip one piece of steel into an opening that is only slightly larger than the beam length.