M1 carbine bottom pistol grip marking identification

Dear members, could someone identify and let me know the signification of the "A" and "5" markings as seen in the pictures ? Markings are located under the pistol grip of a WW2 M1 carbine. Are they US WW2 markings, post-WW2 markings, foreign markings, refurbished markings, arsenal markings ? The stock has a RMC cartouche (right side), a RMC in the sling well and no other markings besides those "A" and "5" markings under the pistol grip. What are they ?? Thanks

https://www.milsurps.com/images/impo...ttomgrip-1.jpg

They are not manufacturing marks and were put on by who knows where or when. Could have been during a rebuild or at a base somewhere. There is just no way to tell what they are or mean. Other then rack numbers or a P proof stamp as that is what is normally found, it's anyone's guess.