To tell you the truth, I am not aware of any LEGO sets which are covering WWII or Seal/Commando/SAS/GIGN/Specnaz
era and still there are customized weapons for them. If you are referring to the City and it's subcategory Police then I have to disappoint you, but police intervention forces do not use Barret, Grenade launchers or silenced pistols. I won't even comment the WWII era which has no LEGO sets whatsoever and yet BrickArms makes items for them whilst, on the other hand, pirates have around 70 different sets + Pirates of the Caribbean. I can hardly imagine Jack Sparrow holding that crappy LEGO designed flintlock pistol which hasn't been changed for ages now. To put it on the lever, on the one side you have dozens of different pistols and rifles for the second world war era which has no LEGO sets whatsoever and on the other hand you have legitimate LEGO sets of the Pirate era which has one pistol and one rifle, not counting the Brickforge's cute attempt to create something innovative. To go even further with this, there are even printed custom WWII minifigs, which is basically building an entire new era from scratch. If BrickArms was willing to take that risk I'm sure they won't mind giving the established and recognized pirate community some new customized accessories. There are a lot of MOC ships out there, double deckers, triple deckers etc. However, if you want to build ships of that magnitude, preferably 1'st rate ship of the line, you also need different cannons. Bigger on the bottom and smaller on the top. Same deal can be used on fortresses, islands etc. Do you honestly believe that BrickArms pirate goods won't have it's market? Imagine printing customized grenadiers and a customized Napoleon together with his forces. Recreating the entire battle of Waterloo made from BrickArms parts. American War of Independence etc. Possibilities are endless, while battle for Verdun from WWI could be interesting it has a lot less details compared to the battles of the 17'th or 18'th century.
Our community is great and we are all potential BrickArms customers.