1941 garand questions

[RCS]

In Chicago, all National Guard units sent their M1 rifles to Riverside (National Guard Ordnance Unit) for a new barrel. In the armory, all rifles had to have the gas cylinder screw with valve to launch grenades etc, all slings were web. All or most rifles had lock bar sights and spare parts to complete additional lock bar sights, only on the M1D rifles were the later knobs found. Wood was supplied by Riverside. The flush nut or spanner nut was found on imports such as Lend Lease or other imports, veteran bring backs or restorations.
I would guess that before the Korean War the flush nuts were all replaced in most US services rifles. Never heard of a DCM purchase with a flush nut - but it might have happened.