What might "S.A. gear" have been? Here's the context: one of the Archer-equipped troops of 218 Battery (55 Suffolk Yeomanry AT Reg't) made the following technical report: "My guns have fired a considerable number of R.D.C. Ammunition [Reduced charge HE] and as yet, not one round was capable of recoiling the gun sufficiently back for the S.A. gear to operate."
FH 70 operation tips and tricks Mentioned in the middle of this thread. “ S A gear is semi- automatic gear, this opens the breech on run out” See here too :Semi-automatic gear on 6 pounder and 17 pounder
Yes the semi-automatic gear automatically opened the breech and ejected the cartridge on run-out. It also automatically closed the breech once a round was loaded, although I think this was via a separate mechanism. With reduced charge 17 pounder HE ammunition, the breech had to be operated "QF" (i.e. quick firing), which meant that it was opened and closed manually via the breech mechanism lever (BML). Do you know what mark of 17 pounder was used in the Archer, Chris?
Hello! Do you mean to say that the failure of the S.A. gear to function in conjunction with the reduced charge HE was actually by design? According to the manual, it was the QF 17-Pr. Mark II. Chris
No, the reduced charge would have meant that the gun did not recoil backwards far enough, such that the cam could not be actuated when the gun ran out. The Mk.II 17 pounder was closely related to the original Mk.I towed anti-tank gun, and had a longer recoil than the later versions fitted to the Sherman Firefly, Black Prince, Centurion etc. This problem did not affect those tanks, but did affect the Challenger which was fitted with a Mk.II. For the Challenger, reduced charge HE had to be loaded and ejected by manual use of the breech mechanism lever, although there was an attempt to pool all the full charge HE ammunition for Challenger use, and all the reduced charge HE for Sherman Firefly use. The general principle of breech operation and the semi-automatic gear is covered in the Comet Technical History book that you have.
Ah, what I should have said was, it was expected behavior with the Mk II gun and the reduced charge rather than a flaw in 218 Battery's guns.
