I once had one of these "pilot guns". Mine was marked as "Model 645" on the receiver, but the receiver had the one-piece, wrap-around, delrin stocks like any other Model 4506. Mine shot like a parts gun... as in parts that were not fit for a production gun. It was reliable, but it did not shoot groups at 25 yards, it shot patterns. I traded it away as fast as I could.

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VCDL, GOA, NRA