Dear Manolo,
I guess my point was missed
.
When i mentioned 'rifle' was in the generic sense, intended to distinguish between the ancient musket (rest) and the XIX century thing, as shown in your pictures.
When coming to shoulder arm terminology itself, as you approach, let me tell you this is one the things that have completely different names in castillian and portuguese.
The generic and massively used term over here for shoulder arm is 'espingarda'.
It fits practically all situations, even in the case they have a specific name.
For the hunting arm, you may say 'espingarda de caça' in alternative to the term 'caçadeira'. For the modern military arm, you may say 'espingarda automática'. You also use the 'carabina' term when you wish to distinguish dimensions, but only in the context.
So we don't use 'fusile', 'escopeta' and even 'mosquete', although we use the late for ancient stuff, as in other languages.
Apparently the term 'rifle' is used in Brazil, but this is one of their an americanisms, and not coming from the portuguese.
Hasta luego.
Fernando