use ctrl+r to pick the selection tool, select the gun while on the correct layer, then at the top go filter>adjust>hsv adjustment
17:34
if hsv adjustment doesnt fit your needs use the "contiguous area selection" and tune fuzziness to select the part you want, then b to select brush and paint over it
1
Cammodude
if hsv adjustment doesnt fit your needs use the "contiguous area selection" and tune fuzziness to select the part you want, then b to select brush and paint over it