Your comparison isn't correct because you cannot just go like that and buy top military grade technology, that is naval. I mean, considering what they are used for and what they are at first place. We're talking about single guns here.
We're really good with Rogues, just so you know. We're allied with the only and currently active Rogue group but that isn't official. So, I wouldn't see any problem there.
The other? Well, the Junker guns aren't any kind of top military grade weapons. Those could be found anywhere on the black market, as well as the Rheinland civilian guns otherwise, they wouldn't be there. Junker bases are supposed to be places where black marketing happens.