LT1,
Did you mean your slingwell is marked TRIMBLE over TN instead of TH?
I too have a stock with a sideways I stamped but its a RSG with Inland CC. I'll post pic below. My understanding is the stock maker stamped the slingwell then shipped the stock to the carbine maker. After completion the maker would stamp their CC on the stock....... meaning accepted. If your stock has the Inland CC, sounds as though it's possible someone added the NPM stamp later on. JMO.

Zaugau,
Your's is the first I've seen marked with the T.I.
Trimble for Inland (?) Must be because that CC is surely a real Inland stamp.

Wulf,
Sorry about your loss of a nice stock. Do you recall if there was anything else marked in the slingwell?

Firstflabn,
I misplaced my copy of Warbaby with some precious notes sometime back. Thanks for that input.

Pictured below are 3 RMC to Inland stocks owned by friends, all are Hi-woods.






Here is the Robert Irwin made stock I came across that originally had a rack number painted on. After stripping it I found a partial Inland size CC on it. It also has the green ink stamp inside the slidewell. The ink is the color RSG used not the same as the color used in early Inland stocks. It's marked with a upside down RSG with a sideways I. I passed pictures of this one to Marty at the Carbine Club.
Has anyone ever seen anything about RSG stocks to Inland in Warbaby?
I've thought about selling this one because I don't need it.
But how do you list it?
A RSG made for Inland stock? With a Inland size CC ?

It's the right one in this first picture,


Bottom one here....





After refinishing.......




I'm more or less a wood and markings nut. I could be happy just collecting stocks. The metal that makes them go boom is a plus.
Thanks to all for your help. It's appreciated

Cheers,
Charlie-painter777