M5 bayonet and M1 Garand

[BEAR]

Bear,
An original real USGI WW-II single slot gas cylinder screw has a center hole that measures approx. 0.240 to 0.245.
The later cross shaped poppet valve gas cylinder screw has a center hole that measures approx. 0.280 to 0.285.
The M5 stud measure .280 [approx.] dia

Additional Reference from Bill Ricca's website: Bill Ricca's Gas Cylinder Lock Screws Project

Thanks for the reference and measurements
BEAR