20pdr Sherman feasibility

[Lascaris]

Just thinking out loud. If in the late 1950s French and Israeli engineers could fit the 105mm F1 gun in the Sherman tank creating M51 is there a technical reason someone could not create in the same period a variant with the British Ordance QF 20pdr gun? Was such a conversion proposed in the period?

 

[riggerrob]

Probably need a longer turret ... like an M60A1.
Remember how the Sherman Firefly got a steel bustle welded onto the back end of its turret? I suspect that part of the reason for the bustle was to balance the heavier gun and ease the load on traverse gears.

 

[Apophenia]

Since the 105 mm Modèle F1 could be squeezed into the Sherman's late D82081 turret casting (aka 'T23' turret), it is highly likely that the OQF 20-pounder could too. However, keep in mind that compromises were required to fit that French gun into this turret. The Israelis cut down the 105 F1 barrel (from L/56 to L/51) and fitted a multi-baffle muzzle brake. The point of both mods was to reduce recoil length.

Obviously, reducing the 105 F1's muzzle velocity would have also reduced the gun's performance in the M51. Presumably, similar measures would be required to get the QF 20-pounder into the M51. These, too, would come at the expense of gun performance.