Originals are green, three rib, hollow back with sprue dimple in the center. Those black ones are post war versions if not mistaken.
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There is a guy in Estonia with a whole stash of originals that posts on ebay often enough. Just remember how to spot originals and you will be fine. I may even have a few left, unsure.
I've had nothing but good luck over the years from European sellers. As long as you know what you're buying. For $5 per cover he has some real nice ones. I've dealt with him over the years for rods, hoods and covers. Pickings are real slim nowdays. I will try to remember if/when I stumble across any.
Over the years the rubber remained pretty dang strong and pliable but always put them in hot water for a bit before placing them on a rifle and don't leave them on continuously as they have tendency to split.
And be careful not to shoot them off at the range...3 lost over the years.
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