A flintlock pistol ... with a Portuguese lock.

[fernando]

Originally Posted by Dmitry

I don't know anything about Portuguese firearms. Was this a regulation pistol?

Regulation means what it says: regulation. In the context, the rules for weapons uniformization ... be them Portuguese or other.
This is when rules are issued to describe the (new) military patterns to be used, whether the weapons are made at the arsenals or when soldiers (officers) are supposed to acquire their own pieces in private workshops, all obliged to follow the same design and basic characteristics.
Consequently a pistol or a sword being a pattern of a determined date, potentially obbeys to the regulation of the same date.
In some cases, officers could have their swords made with the regulation hilt design and use the blades of their ancestors, for honour or sentimental reasons, as long as those (blades) did comply globaly with the regulation measurements.
Also some high rank officers used to be recorded with pistols of a model not complying with the current regulation, whether because they (pistols) had a better performance or simply for show off. But you know all that, of course.
Fernando