Massachusetts National Guard M1 Carbine?

I found a Quality Hardware M1 carbine that has a brass disk on the bottom of the pistol grip that reads: State HQ...72...Mass. NG.

I was just wondering if anyone had seen such a disk on a Carbine stock before. I'm sure the 72 is a rack number.

The Carbine:

Serial #4745XXX
Underwood 12-43 barrel.
J-marked replacement stock, small rebuild p on the grip. Ordnance wheel cartouche next to the J in the sling well.
Two-rivet Marlin MU handguard.
Q-TX stamped trigger housing.
Type II HI milled rear sight.
Winchester front sight.
SI type III front band.
Inland flat bolt.

No evidence that a flip sight was ever installed so I was also wondering if it also left the factory with a Type III band as i read some later QH carbines may have.

Inland and Winchester didn't start using the type three bands till November 1944 and QC stopped production in April 1944. They did get a contract to make replacement type 3 bands later on but they also sub-contracted that out too. Some of those may or may not have gone to Winchester during 1945 production.

As to the rear sight. The barrel date would be close to the production date of the carbine. Most likely about January/February. The adjustable rear sights didn't start till about March/April 1944. But since it went through a rebuild it's had to tell one way or the other.