Steph,
I found the following information in Erik Pilawskii's 'Soviet Air Force Fighter Colours
1941-1945'. This book was published in 2003.
Page 14: " Some new evidence (largely the work of the M-Hobby authors), and
recent examination of physical samples, has revealed that in the 1930s, many VVS
aircraft were finished with an interior aviation lacquer named A-14 (FS26187) and
there was a nitrolak version dubbed A-14F. A-14 laquer was labelled 'steel', and it
had a dark grey colour somewhat like AMT-12, with a hint of green."
" In the late 1930s some factories began to paint their interior - especially on
aircraft with unfinished metal surfaces or painted with aluminum dope - with AII
Aluminum (FS17178) lacquer, " " The 1940 Camouflage Directive and the NKAP
recommendations that accompanied it, must have thrown the matter into utter
confusion at some factories. True, steel tubing, armour plate, and other metal
structures were being coated with Metal Use Primer far back into the 1930s
(or even before) and continued to be so; but when factories decided to paint
the interior surfaces a uniform colour, the NKAP recommendations were a
muddle."
Personally, the above information I find a little confusing. But I hope that
it might help you.
Notes:
1. Metal Use Primer is a mix of FS3464 - FS35622. Erik continues by saying,
" There is no good match in the FS system for this colour; if white and grey is
added to FS34350 it may be possible to mix the correct shade." Erik lists the
color as Munsell Colour Match: 10.0G/9.10/6.0.
2. I have no idea what the Munsell Colour Match guide is.
3. Erik Pilawskii is a very opinionated author, in my opinion.
4. Erik is somewhat biased when comparing Russian aircraft to other nation's.
Hope to see your builds soon, Jeff