Material of Bf 109 Gun Troughs

[Roger Gaemperle]

Hello,

I read somewhere that the Bf 109 gun troughs were made out of steel. Photos of the unpainted Bf 109 G-10 cowling published in Ken Merrick's German Aircraft Interior on p. 202 show a different material.

Was it really steel? Is there any wartime source that confirms this? I couldn't find any reference to steel in the Bf 109 manual nor spare parts list.

And if it was steel, was it due to the temperature of the engine block or due to the blast pressure from the guns?

Thanks,

Roger