If you are looking for .50 cal rounds and links, Mission Models makes empty shells and full rounds with links in PE/brass that can be built up pretty nicely. They look good, but are pricey and are a real female dog to bend the links to shape.
You can see a review of them here.
I prefer thin plastic rod, painted and cut to length. You can see how they can turn out below.
Gino P. Quintiliani - Field Artillery - The KING of BATTLE!!!
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