Welcome to the forum. When you get a chance the net time you login, stop by our "Introductions" area.
You do know that "clips" are used to feed magazines. If you are using the word "clip" in place of "magazine", there are people here who pick up right away that you are not too familiar with firearms parts.
Could you replace the tube (your spell checker used the word "tub") and have a magazine feed?
Yes, but, there is a lot of work and machine time involved. And parts modifications, too.
Would there be any advantage to coverting a tube feed to a magazine feed?
The only advantage is would provide is for quick loading.
It would be cheaper to purchase a good AR platform rifle.
"A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."
Life Member NRA
Life Member NAHC
Former President of the ECPT (Eifel Combat Pistol Team)