I think that, on the whole, the provision for modern guns is ample. My own bias is towards British weapons, but it might be worth thinking about something which would support as wide a use as possible. 9mm Browning Hi-Power -- used by both British and German troops in WW2, and replacing revolvers in post-war British service. MP18 and Lanchester -- early German machine pistol, the Lanchester was a copy manufactured in Britain and used by the Royal Navy. A similar, if not identical, design was used by Italy. I can never recall the names, but how about that Russian sub-machinegun with the drum magazine. PPSh? The FN FAL -- one of the standard 7.62mm rifles of the post-WW2 era, used all over the world. You haven't mentioned machineguns, but the German MG42, in improved form (details such as ammunition feed, and a change to 7.62mm NATO) is still in German service. Also, if you do the Bren gun, remember the later reworking to fire 7.62mm -- obvious differences are the magazine and muzzle. And the Lewis gun. Which was carried by an Imperial Stormtrooper of Mos Eisley in the original Star Wars movie.