To the OP, Colt is selling its snake line in the US nowadays, and there is renewed demand for them. You might be able to export it for a better price than deactivating.
When I cleared my father's estate I found 1 handgun that turned out to be stolen; two that were previously declared lost; and papers for two more that could not be found. There are three others stuck in the estate which cannot be cleared because I'll be damned if they go to the shredder.
The problem with estates is they are provincial and firearms are federal. I've written my MP and MPP to highlight the dilemma their collective presumptuous decrees have created. No word back, but the matter bears reinforcing. I suggest writing to your MP to have the handgun registry opened for inheritances. Afterall, there was a clause for many years that allowed heirs to get pre-1945 Prohibiteds.