It isn't silly at all. You do buy a lot of foreign arms. From the German gun on the Abrams to the Italian pistol your army uses as a sidearm, most of the US Army's weapons are of European origin (license-produced in the US of course).
As I already said we do buy from, and develop with, allied nations over foreign arms. But its not "a lot". And the Abrams isnt one of them, tho I think its reactive armor may be made under License from the Brits, possibly its main gun from someone. America accounts for 44% of the worlds arms trade, Russia 17%, France 8%, the UK 5%,Germany 4%, Italy 3%, other Europe 10%, other-other 4%. Of all them, offhand, the only ones we co-develop with is the brits, the Aussies for some ship work on one system, I think the Swedes for one gun system, Norway for one missile system, and thats about it. Its a very small %, tho an important one and I for one hope our co development and even purchase from good friends continue as long as it add capability and saves money.