From a pal who has an A-5 book. Sorry, I don't have the title or author. Info on chamber length is good...
Could find no specific mention re. 16ga on same receiver as
20ga. however on pg 110: "Part of the forward edge of the receiver is milled away to accommodate the 16ga cartridge
stop in fig, 110-1. The 16ga Standard, Sweet Sixteen and 20ga Light Weight used this system throughout production."
Other info re. chamber sizing on 16ga., in section on Standard
Weight 16ga.: This gun was developed as a lighter option to the 12ga. Auto-5. FN used the 2 9/16 inch (65mm) chamber on all 16ga. Auto-5's until May 1940.
Page 151 same section: "Records are unclear on chamber size for 16ga, Auto-5's sold to Allied soldiers following liberation of Belgium in 1944. Also unknown was the chamber size of this model that FN sold to markets other than the US. August 8, 1958 FN sales materials for the Auto-5 indicate the following: The 16ga. barrels were until recently chambered for 2 9/16 inch cartridges. The conclusion from this statement is that FN supplied some markets with 2 9/16 inch chambered Standard Weight 16 and Sweet Sixteen Auto-5's until the late 1950's".
"Beginning January 1957, Browning imports of the Sweet Sixteen were chambered for 2 3/4 inch shells. The receivers
for the Standard 16 and the Sweet Sixteen, chambered for 2 3/4 inch, are both marked with an "X" preceding the serial number. The barrels are marked for 2 3/4 inch shells and the
"16-70" chamber size indicator is stamped on the left side of the barrel near the barrel extension".
Also sending an order form from Wet Dog Publications for a Browning Auto-5 Shotgun book. It's a pretty inclusive work
that I'm sure you'll enjoy. Have made copies of those pages covering 16ga. both Standard Weight and Sweet Sixteen and will post them to you via snail mail.
