This is a project that I swam my brother to do to your airsoft replica, is a Picatinny rail for scope 34mm in diameter, it is advisable to take three Torx screws metric, but I have not found in the photos look planes, but I came to find allen. There is a cap that is recommended to make two one for each rail. The screw must be less than 5 metric ade length of more than 30mm, which is recimienda cut and put the lid can not be metric nut 5 which we introduce. We also need to put metric nuts 3.
All nuts come very fair is advisable to use a heat source (soldering) to enter nuts encased remain well seized.
Lower picantinny measures on which it must tie NATO action.
I attached a photo that I illustrated for me the replica and the other was mounted photo is like.