P-51 w/ 4 X 20mm
 

Was the 4 x 20 mm guns used in the P-51 or was this experimental?

Re: P-51 w/ 4 X 20mm
 

Only the XP-51B had four 20mm cannons.

Production P-51B and C had initially four 0.5 inch machine guns

Re: P-51 w/ 4 X 20mm
 

I believe only the P-51 (post XP-51, pre P-51A) had the 20 mm Hispano guns. The first experimental P-51B was essentially a modified RAF MUstang II (modified with Merlin installation and modified cowling) and no version of the P-51 afterwards ever mounted 20mm.

The NAA version of the experimental P-51B lowered the wing seven inches to improve the cowl line and re-designed the lower radiator cowling plus changed the radiator core.

Re: P-51 w/ 4 X 20mm
 

Re: P-51 w/ 4 X 20mm
 

British ordered 150 aircraft, NA-91/P-51, 41-37320-37469, FD418-FD567.

93 aircraft where shipped to England as Mustang IA
FD438/41-37340 - FD449/41-37351
FD465/41-37367
FD470/41-37372-FD509/41-37411
FD528/41-37430-FD567/41-37469

55 retained by USAAC for photo recon variant P-51-1NA, later F-6A.

2 aircraft retained for Merlin modification (NA-101, XP-51B).
FD450/41-37352 & FD519/41-37421

Regards,
Mike

Re: P-51 w/ 4 X 20mm
 

Did these saw any action in the war?

Re: P-51 w/ 4 X 20mm
 

Yes. The USAAF ones in North Africa/Italy. The RAF ones in Northern Europe.

Re: P-51 w/ 4 X 20mm
 

The RAF Mustang Mk.1A armed with 4 x Hispano Mk..II* 20mm cannon served in front line service from June 1943 until August 1945. They served with a number of the RAF's tactical reconnaissance squadrons and were well regarded by the pilots who flew them in that role.

There is documentation from 1944 and 1945 indicating that the RAF was still interested in Mustangs, including the Merlin engined variants, to be armed with 4 x 20mm cannon. However the expediencies of quantity of production and not wishing to delay deliveries meant the 0.50in HMG armament preferred by the USAAF was accepted.

Re: P-51 w/ 4 X 20mm
 

Colin - there were no significant changes to the gun bays of the XP-51 through P-51B/C so if Hispanos were feasible in the earlier series it should have been an easy field mod at worst to replace 4x50's in the inboard and center gun bays, and simply remove the outboard guns.

Is there any contrary documentation to indicate why RAF didn't do this? IIRC, the RAF modified the armament for the Mustang I to include 30 cal.