I know they were issued to bomber and transport crews, not fighters. Fighter aircraft carried a Kar98k mounted on clips inside the fuselage. Only aircraft that operated in North Africa and the Med were so issued.
The 'black men' Luftwaffe ground crew, so named since they all wore black coveralls, would remove most non airframe items such as rafts and other survival gear after the end of operations for the day. The desert cools off so much at night that dew would be a problem, so one can safely assume that the rifle would be removed as well. Something such as special (even then) as the M30, its care might be assigned to a flight crew member.
Next op, the survival gear goes back in the airplane, whether or not the same M30 or Kar98 went into the same airplane we will never know. The M30 cases seem to not to be marked with an airplane call sign.
For example, if a M30 case had stenciled on it 3Z+FR we could safely assume via Luftwaffe records that that case would have been assigned to a Dornier Do17E that flew in North Africa with KG77 in 1942. I have never been in a Do17 as none survive (except one found recently off a beach in sea water in England) , but I have been in a Heinkel 111, a ex Spanish bird that came to YYC many years ago. It was so cramped inside I could not imagine where exta gear would even be stowed!
No cases appear to be so marked with aircraft numbers. Fantastic item nonetheless!