Holes Under Butt Plates, Help Needed

[painter777]

I have examples of these stock makers with the number of holes under the Butt plate:

1 Hole:
S-HB, OI, HI, RSG (SG), RSG (S'G'), IR, RSG TO I (TRANSFER), RMC, RMC TO I (TRANSFER), RMC B, QRMC, TRIMBLE FOR NPM AND SG.
SJ, LW, LW-U, LW-B, P-U, JL-B, JL, IR-IP, Circled K often thought made by Keystone, HQ.

3 Holes:
WRA, SC-B, S&C-U, M-U, BR-B, J, SA, M with Bomb in slingwell. P-J


Would also appreciate any information on Butt plate holes from any replacement stock that has a marking in the sling well... Like just P, .. etc.
So we'll know the maker.