Hey guys,
I have been looking for a 75mm M-4 jordi rubio barrel at local hobby shops,and at vendor tables at a local swapmeet,but the only thing close was the 105mm,this gun comes with the mantlet, and I was wondering, If I changed the mantlet,and used the white metal one with the metal barrel,could I use the 105mm barrel? Thanks!

Kinda depends on which kit you are working on. If it's a late M4A3 or M4, you can use it, but need to add the extra ventilator to the top of the turret.

By late. I mean a large hatch, wet stowage lower hull and a high bustle turret. If you have the Tamiya "Early" M4, that is a NO-GO.