Swift and at least one other operator use the J&J Apex adapter on their DW barrels, so I thought I would put together a HOWTO.
Here's what you need:
It would likely also work for any 7/8 OD barrel.
I think I wrapped it with about 3 wraps of electrical tape.
The electrical tape has two purposes.
1. To make the adapter fit on the barrel snugly so it doesn't wobble.
2. To protect the CF barrel from being damaged by the 3 set screws that secure the adapter to the barrel.
When you install the set screws, you just want to snug them enough to secure the adapter so it does not spin. DO NOT TIGHTEN them down with a gorilla grip or you may cause damage to your barrel. I take NO responsibility if you do this mod and damage your barrel.