Very nice Marcus.
Parker Bros. did not lengthen the chambers of 16g guns until the 30s, and typically cut the chambers slightly shorter than the 2 9/16" shells of that era.
There is an easy way to measure chamber length using a 3" x 5" index card, rolled lengthwise, and slid into the chamber. It will partially unroll and expand to the chamber diameter.
Gently advance the card until it stops at the end of the chamber (where the forcing cone constriction starts), use a pencil to mark the card at the breech end of the barrel, and repeat the steps to see if it always comes to same spot.
Then use a ruler to measure the length marked on the card.
The chamber must be clean, and it works best with a new 3” X 5” card.
There is NO modern data regarding the increase in chamber pressure using 2 3/4" 16g (and 20g) shells in short chambers. Certainly recoil may be increased if the shell mouth enters the forcing cone.
Some of today's 16g hulls however do measure shorter than 2 3/4" (after firing).
The hang tag that originally came with your gun specified 2 9/16", 1 oz., 2 1/2 Dr.Eq. shells.
The Parker “Overload Proved” stamp first appeared about 1925, but Parker literature from the 1890s confirmed that barrels were proved in house; in the 30s to a pressure of about 17,500 psi.
re: what loads are safe to use? Bad things happen to guns in 100 years and your gun is likely well past a check and clean by a double gun specialist, who could check the head of the stock for cracks, the bore with a bore scope, and measure the chamber length, end of chamber wall thickness and barrel wall thicknesses.
Scroll down here about 1/3 way for more about short chambers
https://docs.google.com/document/d/1...A/edit?tab=t.0
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