I was wondering if anyone could tell what the practical shooting differences between Hydro-Pneumatic recoil cannon and Hydro-Spring recoil cannon? Is there a 'harsher' recoil or recovery? Is one faster than the other? Is one more suitable for mounting on an armoured vehicle?
I think you are right - the only gun I can think of which had pneumatic recuperation was the 15cm sFH 13 and that was
a response to problems with recuperator spring breakages.
Another aspect is the cost of production of hydro-pneumatic systems - these required very accurate machining else they didn't work.
There is somewhere on this forum a description of the machining steps the Singer Company used to produce the recoil systems
for the US built Mle 1897 field guns. I'd assert the machining and the cost of a hydro-spring system would have been a small fraction
of the cost of the Mle 1897 hydro-pneumatic recoil/recuperator.
I'd also point out that the Mle 1897 is held up as an example of total recoil absorption and it was, under ideal conditions. Where the ground was water saturated,
even with the wheels locked, the gun would slither back anything up to a meter.
From memory the Mle 1897 recoil piston was essentially put together in a craftsman process unlike the rest of the gun. The USA had immense problems machining the tolerances.
