Solid vs Poppet gas cylinder screw

Anyone know when SA switched over to the poppet gas cylinder screw from the solid?

Thanks

Post-WW II. There was concurrent production of both from Jan, 1944 through the end of 1945.

I would have said that the single slot was gone by the end of 1944. I didn't realize they were still using them through 1945.

There were suppose to be replaced in early 1944

The poppet valve lock screw was used in Rifle Production. Records of inspection show them by Jan of 44, but my contract records show them in April of 44.

The non-closing valve lock screw never was used in rifle production. Very few were produced and they were handed out to units for use by Grenadiers.