This may or may not help, but here goes.
In 2002 U.S. dollars, the Blue Book lists:
Harrington & Richardson
FOLDING GUN
- 12, 16, 20, 28 ga., or .410 bore, single shot, hinged frame, barrel folds against stock. Mfg. 1908-42.
Grading 100% 98% 95% 90% 80% 70% 60%
$195 $175 $150 $125 $100 $85 $60
Add 75% for 28 ga. or .410 bore
The book identifies the model as originating in 1908. I do not know if there was a predecessor for this model, or if there is, whether it would be worth any more. Taking into account inflation, and conversion from the American dollar, and given that we are talking about the same model as listed, I would estimate the value of your .410 as priceless - one of a kind. No other .410's came from your grandfather. Halt the rust by lightly rubbing with oiled, brass or fine steel wool. Clean the bore, and check out the gun for flaws. If possible, go shoot a grouse with it every year. As time passes, the monetary value of the gun will become meaningless.
Sharptail
