Looking at the 1077 Freestyle and RepeatAir, neither one looks like they'd take a silencer. But, there may be threads on the inside of the shroud that you might be able to take advantage of. First, I'd call Crosman and see what they say. Also, you might try DonnyFL and see if they would have an adapter for your rifle.
Crosman
Toll free: 800-7AIRGUN (724-7486)
Direct: 585-657-6161
DonnyFL
https://donnyfl.com/
Donny Du is a great guy and he & his staff are very knowledgeable.
Mondo
