Milling slots on round tube

[woodchucker]

I would consider putting a tight fitting wooden dowel right thru the tube before cutting any slots.
When using either the mill vise or clamping to the table, it will help avoid collapsing the tube.

-brino

expanding on this idea,...
take the dowel cut it at an angle like an adjustable parallel.. sand it, put a piece of thin wood the size of the saw kerf in glued to one side.
put it in the tube, and squeeze it from the ends, it will hold tight. use a clamp, or tail stock ..
just a thought.

 

[agshooter]

The Rose Index worked great to make a new handguard for my rifle!

Taking light cuts, I was able to make all the cuts needed while clamping the round tube in the vise. I know, not the best way to go, but it worked for me.