Musket components found in treasures

[qualkonn]

I've found these components when finding treasures from treasure maps and I don't know what to do with them. They can't be sold or discarded and I can't find anything in the forums.

Does anyone know how to use these?
Thanks.

 

[Aldodrem]

I think its for the DLC musket that you can get?

 

[qualkonn]

I think its for the DLC musket that you can get?

Thanks for the response, how do I get it? I have found many other treasures, but no more parts, do I need to take these parts to someone? if so where?

 

[Iguferon]

These parts are for the old arquebus. You use the parts one by one to upgrade it while it's in your inventory.