1942: What if the American Hispano HS.404/M2 worked?

drgondog said:

There are so many Encounter reoprts describing more than 600 rounds expended (i.e. more than 125 rpg for four guns) to shoot down a fighter that one has to wonder whether the exact same placement for the four gun battery would have resulted in a much faster kill. I suppose so, but by same token I suspect the number of 3 kill+ encounters would have also fallen off due to running out of ammo faster.

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The question is if the 20mm could have achieved success more quickly.

Perhaps it was a case of pilots knowing they had plenty of ammo, and were less precise in their use than they might have been?

drgondog said:

Post D-Day I wonder how much more effective 4 x 20mm (or 6x) would have been in a Jug for CAS than the 8x .50 cal.

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I suppose it depends on targets. For tanks and armoured vehicles I suppose that the 20mm would be better, but for troops and unarmoured vehicles the 0.50 would have been more than adequate, and would give more rounds to use.

drgondog said:

The LW pilots I have discussed this with vis a vis P-51 vs Me 109 or Fw 190 commented that perhaps many more German fighters would have fallen had the 51 been armed with a reliable 20mm and conceeded that the trade off would be the degradation in airspeed and resultant range associated with a 3=% increase in drag for the 4x20mm configuration on a P-51B.

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I have often wondered the same. Would be nice to see a thorough study based on reports of this sometime, but it'll probably never happen. But I have read many accounts of German pilots being shot down in 1944 by mostly P-51s but still being able to crash land or bail out. It kind of gave me the impression if they were hit by cannon fire it might've turned out differently. If a 20mm shell had punched into his cockpit that day, Rall would've lost more than a thumb... (thank god he survived, don't get me wrong).

As for the increase in drag, 6-8 mph doesn't sound so bad to me, still has the P-51 coming out on top for a long time. Range reduction would be more interesting, but I kind of doubt it will affect the capabilities too much.