If the rail screws or rivets protruded into the compression tube you'd have to mill a slot into the piston roof. The Beeman R10 used that and it became the Achilles heel of that model. It wouldn't be pretty ugly, but you could spot weld a steel rail or weaver mounts on there. That's if you could find fairly close fitting ones. The tube will heat distort somewhat depending on the welders talent but it wouldn't be terrible, being away from the sealing area. Just a thought.Personally I'd try to find a new front sight or muzzle piece and leave it unscoped.
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