How can I unlock new weapons to buy?

I was browsing the catalogue at the local gunsmith and I noticed that several weapons like e.g. the Carcano Rifle are currently locked (the message is simply "this item is locked"). I can't buy them even though I have the money.

How can I unlock these weapons? Is this tied to story progress or something else?

1

2 Answers

Many weapons are only available after completing certain missions. The Carcano Rifle in particular is unlocked after completing "Goodbye Dear Friend"

This German website says:

Rob houses or shops controlled by enemy gangs. You can find such shops when you walk around in a town with your eyes open. Often, weapons can be unlocked there.

Original Text:

Wie schaltet man neue Waffen frei? Überfallt Häuser oder Läden, die von feindlichen Gangs kontrolliert werden. Solche Läden findet Ihr, wenn Ihr mit offenen Augen durch die Städte geht und Ausschau haltet. Oft lassen sich dort Waffen freischalten.