A flintlock pistol ... with a Portuguese lock.

[fernando]

Originally Posted by Dmitry

Thank you. I did not know that ...

Don't take it wrong; i was referring to the connotation of the term, in its idiomatic expression.

Originally Posted by Dmitry

... If this was a regulation piece, it should be easy to research...

I don't think this is a regulation piece; this assuming that pistols were already a regulated weapon in Portugal by 1781 (i intend to check that).
However and despite Master Bartholomeu has been attached to the Royal Arsenals, it wouldn't mean that he ceased making pistols for private use; he might even already be dismissed from the Arsenal by that date. Besides, if this were an issue weapon, i'd say he would mark it with reference to the Royal Arsenal, and not just to Lisbon.

Originally Posted by Dmitry

... Lack of decoration on the stock suggests that it could've been an issue weapon, in which case you should see similar examples. ...

The stock is not decorated, but the barrel is. OTOH, these items are very scarce, easier to find in private collectors hands and not exhibited out there, i'm afraid.

Originally Posted by Dmitry

... The lack or a band securing the barrel to the fore-end of the stock is also unusual ...

Not really unusual; if you have a look to this period holster pistols in general, namely British, as large as may be, you will notice that the significant majority don't have a barrel band, as they are secured by pins or wedges to fore-end hooks.

Originally Posted by Dmitry

... but I don't know anything about Portuguese firearms...

You're not alone; my knowledge of Portuguese firearms is the same as about those from other countries: barely residual. But i love to learn.

Fernando