William, Many molded original holsters have a nice shape and are hard. I would need a lot more information to determine it's authenticity.
Did Simpson's sell it to you as an original? How much did you pay? If Simpson's said it was original I wouldn't necessarily worry too much about it. I don't believe they would intentionally cheat anyone.
If you would like to send me a photo or post one or two on the Forum I can tell you for sure.
I like to see the full back and one of the front with the top open.
Jerry burney
lugerholsterrepair@earthlink.net