Used Marble Sight Set 995001 to mount the Marble tang sight [marked "Browning"]. Screws fit just so.
(2) 10-32 x .342 for front and rear screw. Set also includes an 10-32 x 2.060 [which is not needed]. Marble's sight list does NOT show the long screw... But it isn't needed...
Only the 78 is tang-free and one of the complaints about those rifles.
I machined a base so I could use my Soule tang sight on my Browning TH in .38-55. That same base fits my original Low Wall .22.