Externally/barrel mounted breacher

[JeffCooper]

I'm about to send a bunch of stuff to Vang Comp for their treatment. I actually have a Remington breacher choke. I'd prefer NOT to tread the bbl to take a choke. Are there some fierce attachments that three on to the OUTSIDE of the barrel? Essentially I'm looking for a very evil "eye poker outer" that I can attach to the outside of the barrel. I hate the idea of a mag-tube as the tube is so thin...and I hate the idea of tapping an 18" bbl for an actual choke. However, if I could find a eye-poker-outer that bonds up to the barrel, that would be perfect. Recommendations? Sources?? All hel appreciated!