Drop in baffle system with airstripper and end cap. This is similar to the style used by Benjamin for over 10yrs. Source a 20mmx30mm spring to place between the airstripper that goes over the end of your barrel and the first cone in the stack.
Pictured below is the tried and true Benjamin system. This stack has been adapted to the AV Avenger.
The author marked this model as their own original creation.