Been looking everywhere but not much info out there. Are there different versions of this gun up to the 1860's?
Hi Mark, yes there were, McConnell, pages 58 - 61, has the best account.
Boxer lists three as being in service in 1853, they are 84, 75 & 67 Cwt. The closest to your measurements is I believe the 42pr of 67 Cwt. Trunnion dia in all cases is 6.97" & trunnion length of all is 6.0".
Re your diameters 17.5 = 17.52 ; 19.125 = 19.3 ; 21.75 = 21.87
Re your lengths 30.375 = 29.74 ; Center of trunnion from beginning of chase is 6.94 = very different to what you would have (your 30.375 length does not tally with your running measurements if I'm reading them correctly). A glance at your photo shows that your trunnion location measurements are well out, the trunnion shoulder is much closer to the chase than 8.25".
Please confirm the pattern you are after is 9' 6" long (the other two patterns are 10') Note, length is measured from base ring to muzzle (it is not overall of cascabel etc)
Regards
Adrian