You should be able to make it work since it's a nutted barrel. If there's not enough threads left on the barrel for the nut to move far enough forward due to the longer tenon, the nut could have the forward threads relieved so it's not an issue-provided you've still got enough threads engaging with the nut to lock securely in place. Spin it on and see...I just hate to take off the 300 Rum barrel it shoots lights out right now .
I guess it's no worries really the 300 Rum is a Remage set up ..it will be easy to put on another action.
Thank you guys !
Rum Man