Hi Dash,No , 4” tube will not work according to the original the max tube size is 3”.
Here is the original listing:
There is a piece of 4” tube on the side for scale of this jig. I suppose it would be possible with some creativity .but that is not what this unit was designed for.
View attachment 388645
I have the High Power Rocket jig but lost the instructions over various cross-country moves. Do you have a copy of the instructions on hand? Thanks!