Afghan guns captured at Ali Masjid
From my Sgt. Guinness.
Your question peaked my interest in the Afghan artillery. I simply painted mine brown, however that may not be correct. I'd sent you the photo of the rows of guns captured at Ali Masjid. These are typical of the types af artillery they fielded.
According to what the Mad Guru has told me the majority of the artillery came from the British with a little from the Turks, thus them being the regular British Blue Grey. You could also have some painted green as if the Russians has provided some.
Additional from the Mad Guru:
A combination of British military aid and buying new high tech RBL Armstrongs through Turkey. There are no pics of the RBL Armstrongs that I know of - also I don't think there was any difference in paint scheme of Afghan guns based on their origin - whether gifted by Britishs or purchased on their own from European or Ottoman suppliers by Afghans. I think they were all painted in British style colors. There is a pic showing dozens. unto hundreds of captured Afghan cannon, abandoned at Ali Masjid I think - maybe another one inside Bala Hissar But only b&w of course Sadly! Lots of small mountain guns, up to field pieces. My educated guess is yes - blue grey. I have never read any different description. The Second Afghan War started over anti Russian fears of a Russian rapprochement with Sher Ali - you could always give your afghan regulars a battery of green Russian style guns.