As to chokes, catalogs state unless ordered different full/full on most 28"-32". Shorter could be improved cylinder/modified. Later guns in the 1940's were sometimes choked modified/full.
Your serial number indicates it was made in 1938 for a hammerless shotgun. At this time the bores should be .660 and the chambers 2 9/16". Be careful in shooting 2 3/4" shells as you could build up more pressure with a higher payload.
The best way to check for choke is to have someone use a Vernier caliper, telescoping gage, or a bore gage like Skeets. I don't like the tapered brass ones as they are not reliable.