Shell Casing Ejection Chute Covering

P-40's in the Aleutian Islands (and elsewhere) used doped over fabric to protect the guns barrels against foreign material and moisture. But that material would be too strong to use for shell casing/link ejection chute covering. What was used for these openings?
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P-40 gun barrels stick out past the wings leading edge. What you are seeing in this photo is most likely a delivery flight. The gun barrel holes and ejection chute openings are covered with tape or doped cloth.

Thank you for the reply and the photos mifur. I'm interested to know what material was used on the ejection chute openings. Your 2nd photo clearly shows something covering the ports on the gunbay access door. I think doped fabric or most tape would be too strong. You would only have the weight of a few links and shell casings to break the seal and it would be very important that seal would give way easily to prevent links and casings from backing up into the gunbay. Has anyone ever seen a T.O. regarding sealing these openings or is this just an example of Yankee Ingenuity?

You've missed my point. The aircraft was being transferred to Alaska and the gun barrels (or extensions) had been removed, the wing openings were then covered to keep out dirt, water, etc., same with the ejection chutes. Once the gun barrels were re-installed and ready for combat there wouldn't have been anything covering the ejection chute openings.