Well, I thought I was over with the AFV club M109A6 Paladin and in my box there are some pieces left, not found on the instructions :
X 1,2,3,4,5,23,26,29
C 32 34 35 36 37 38 56 57 18 19 20 21
B 22 26 27
R 18 22
H 1 2 3
I don't know if someone else here is working on it, but I'm curious to see if I have dirt in my eyes or something...

Or are these unused parts? but nothing mentionned that in the instructions.

I would make an educated guess and say that these sprues are the same in their M109A2 kit

Just see the M109A2 pics here to compare :

http://modelerssocialclub.proboards.com/thread/3939/afv-club-m109a2-howitzer

So these leftover parts are for the A2 variant...

HTH

H.P.