Plutonium

YPCD and.. what the hell is that pfp bro..

Did you map the UV layout? Because PNG mapping is flat, so the game can't distinguish what is the stock or barrel of the gun.
skin base: weapon_acr_col.iwi

Use GIMP, is better for warping.

YPCD Could you send me the PNG?

YPCD You said you used Paint.net. It's great for simple edits, but terrible for this, as it doesn't have good warping tools. I recommend using GIMP.org. Use the original weapon_remington_acr_col.png file, the one you got from imgXiwi.
Create a new layer and paste the PNG onto it. Lower the opacity of the original texture layer to 35%. Use the Warp Transform tool.
click on the edges of the cammo in the reference to create a cage, and then drag the points so that your logo stretches and distorts to exactly match the shape. Export at the same resolution as the original, open run %LocalAppData% and go to /plutonium/storage/iw4 and create an images folder.

YPCD This whole UV warp thing is actually quite difficult, especially in Cod Zombies.