John Cunningham always sends me back any masters of figures I have made for him so I took the forage caps for the HA figures off of other conversions. The ultimate in recycling?
Horse Artillery Gunners - probably didn't wear forage caps on active duty?
Royal Artillery Gunners - I have read by the end of the Crimean War most sported forage caps instead of shakos.
For the Royal Artillery set I needed more heads and since I was taking the heads mainly off of the British Officer in Duffle Coat I thought I would put a peak cap on one of the body to reuse it as an officer. In Timothy j Reese's Uniforms of the British Army of the Crimean War he illustrates a RA Officer in a peaked cap (although not a Duffle coat).
The head twist method does mean that you get to save heads and bodies for later conversions and I try not to waste either.