Names are definitely trademarked but I've never heard of anyone running into issues over designs. For example when Valve picked up counterstrike they renamed all of the weapons but the models are still the same as ever.
Firearms licensing is a hugely complicated area because many currently produced designs are variants or derivatives of designs that are more than a century old, while others are almost entirely new. There is a reason small arms manufacturers (at least within the US legal system) do not have the same kind of design and…