Really, router=right tool for this job. That’s not woodworking, that’s timber framing. Unless you go out and get yourself a slick, a twibil and a couple of ship augers, you likely don’t have the “proper” hand tools to do that job efficiently by hand anyway. You can use a brace and bench chisels to chop it out just like you can use a dovetail saw to crosscut a 2×12, but would you want to? While bench chisels may resemble the “proper” tools for timber framing, they are different beasts entirely. Just like using power tools, there are hand tools that are the right tools for the job. For a mortise like this, which again is more like timber framing than joinery/cabinetmaking, joiners/cabinetmakers tools are not the right tool for the job. Fire up the router my friend.

Nicely done. Yes the Galoots may scoff, but in the end the satisfaction is yours for the having.

Great job.

But I agree, that’s a mighty big hole to approach with a chisel when you have a router sitting on the shelf. The important part is that paring chisel work after hogging out most of the material in any case. Right tool for the task(s).

Personally I’d draw the line at the laser marking gauge, though.

Cheers — Larry