Wire Arc Additive Manufacturing (WAAM) utilizes wire as the feedstock and welding arc as the heat source. While Solid Wires (SW) are common, exploration of tubular wires such as Metal Cored Wires (MCW) in Additive Manufacturing (AM) is limited. MCW offers flexibility for alloy design, but both SW and MCW can create silicon islands on welds, affecting mechanical properties and processability. This study uses Gas Metal Arc Welding (GMAW) in Cold Metal Transferred (CMT) mode to compare SW and MCW deposits with different gases. MCW shows more uniform penetration, potentially reducing lack of fusion in AM layers. A novel approach is then used to modify the MCW to minimize silicate formation, reducing islands on the surface. Comparative analysis shows a significant reduction and change in the location of silicates with modified MCW compared to standard, with mechanical properties in as-welded and after post-weld heat treatment (PWHT) remaining comparable to the standard wire.