Could be one someone made at home, could be one that someone refinished,or could have been one that just had a decal that wore off. Can't guarantee this will be dead on, but here's a starting point at least.

First, get the actual AMO bow length. Get a flexible tape (like a steamstress' or tailor's tape). Start at the top of the string groove and measure along the side of the limb, following the curve. Go through the center of the riser to the top of the other string groove--that gives you the AMO bow length.

Most of the old recurves I've owned got a string 4" shorter that the AMO bow length (although AMO specs state 3" shorter). Dacron only for that bow (B-500 or B-50).

Chad