"if it dates from later than 1925, the advent of the Super-X--and that 3 3/4 DE, 1 1/4 oz load is the original Super-X load--means that your gun
should have been built to take it."
Certainly the top rib extension and rotary locking bolt designed by Alexander Brown in 1883 & 1886 (hammerless) could take it, but as Bro. Larry said, not the wood.
http://www.lcsmith.org/faq/rotarylocking.html 1925 Hang Tag; patterned with 1 1/4 oz. and 3 Dr. Eq. The "standard" Field and Inanimate Target Load from c. 1895 until WWI was 1 1/4 oz. 3 1/4 Dr. Eq., in a 2 5/8" or 2 3/4" case. Of course the Live Bird fellas used some boomers, and destroyed some Smiths. And I believe that explains the shift from Smiths to Parkers and Repeaters by the "Top Guns" by about 1900.
See
https://docs.google.com/document/d/1D8QkBDo-KIQYk2G8lkE-kHLUybB5NJzBahX_eFKEyuY/preview 
The Long Range Wild Fowl WAS designed for Western Cartridge Co. 12g 'Super-X Field' 2 3/4 inch 1 1/4 oz. 3 3/4 dram equiv. shell introduced in 1922. It was NOT designed for the Winchester/Western 1 5/8 oz. 12 gauge 3" magnum introduced in 1935.
I'll freely admit it was a design flaw that Hunter Arms tried to correct
Pre-1913 12g Reg. Frame oil soaked and cracked head of the stock
1936 12g Reg. Frame clearly with more wood
