Call Of Duty Mobile - XM4 Gunsmith with Red Dot Sight. To be honest, for me, playing with the default iron sight with this gun is harder to see than using the red dot. It's better to have better view rather than having full attachments but sacrificing your sight.
Here's the Gunsmith for the XM4 (1st Build) :
-Agency Suppressor
-13.5" Task Force
-Classic Red Dot Sight
-SAS Combat Stock
-FMJ
Here's the Gunsmith for the XM4 (2nd Build) :
-Agency Suppressor
-13.5" Task Force
-Classic Red Dot Sight
-SAS Combat Stock
-SALVO 45 Rnd Fast Mag
For me, 1st build is for hardpoint & domination, because the FMJ makes it easier to wall bang. And the 2nd build is Versatile, can be used in any mode, but it's harder to wall bang.
When I made this video, i was playing on Grand Master I to II right after the season reset, so it's kind of rushed. Enemies are spamming USS & other meta guns XD but i don't think this gun is going to be meta since Type19 performs similar with better mobility. But hopefully with the upcoming Mythic skin for this gun, they'll buff it.