I've inherited what I think is a Belgian guild gun in 16 ga. It's got external hammers and twin triggers, and from the research I've done, it appears to have been proofed for black powder between the years of 1910-1924 (from what I've managed to dig up, a diamond containing the number 16 above the letter c was apparently a black powder proof mark used between 1898 and 1924; the word "choke" followed by what can best be described as a fraction with "16.4" on top and "17.0" on the bottom is a choke designation used on Belgian black powder guns between 1910 and 1924).

There are also some letters and numbers on the underside of the rib between the barrels, and I'm curious whether anyone can tell me whether they indicate a manufacturer, or have some other meaning. Those letters/numbers are:
14 D-R D26 H B 9 3414

Any information that anyone could provide would be appreciated.

Not to detract from all the knowledgeable folks here on AR, but try going to shotgunworld.com.

Those folks over there really got it together on shotguns. It is a very friendly forum.

Thanks. I'll try that.