Are you sure that you have a nylon 66? I think you have a nylon 77. From what I have read the both the grip plate and the buttplate are bonded in place from the factory. They were not meant to come off at all. I also read that the inside of it MAY have 2 screws holding it in place from the inside under the whole trigger assembly. Although that is true, I am pretty sure you have a nylon 77. The 66's came with a tube mag where as the 77 comes with a clip. Pictures of the gun itself and how you know its a 66 would help. From what I have read though, I would be almost certain it is a 77.