After a little messy fix of replacing the wrong duct seal with the correct duct seal I am finally happy with the final results.
I used a metal junction box from Home Depot. It comes with a lid which may be good for storage outside.
[IMG]

[/IMG]
[IMG]

[/IMG]
The Talon Shooting Kodiak .22 at 755fps 15 yds was pushing all the way through the duct seal. It could be due to the 97* temp here in So. Cal. So I placed a .75" MDF board behind the duct seal.
[IMG]

[/IMG]
[IMG]

[/IMG]
The metal box is weather proof, strong and has a lid. A good feature is the lip that holds the lid holds the cardboard as well as the target in place.
[IMG]

[/IMG]
This was not the cheapest method to build a silent pellet trap but as a previous poster stated...stop going cheap...This silent pellet trap I built will last forever....add duct seal as needed.
Adam in SoCal
A.nother D.arn A.irgun M.adman
[IMG]

[/IMG]