Blue print color can change in 357? If change attachments

[Avivshaul]

Hey I want go buy the old scout blue print at the shop that have gold 357 there but there is no barrel attachment on the gun ,and I want to put the long barrel . So my question is if im putting the long barrel on the 357 its will change the gold barrel to black or it will stay gold ?
I wanna know before I buying it
Thanks for everyone