Durango,
I'm not familiar with any firing pin marked R-O.
I've seen RO-Q Recoil Plates.
The Riesch book shows QHMC used Type 1 firing pins marked NL-Q, N-Q, HS and BQ.
Type 3 marked NL-Q, and N-Q.
Taking in to account that QHMC only made their Receivers and yours being so early, I'd lean toward the Rock Ola firing pin as being very possibly original to your carbine.
Rock Ola supplied quite a few parts, stocks etc to QHMC.

I'll check Ruth's War Baby tomorrow.

In the mean time can you,
Show us your Carbine.....
Look at the back of your firing pin: Can you tell if it's a Type I, or III ?
And just curious where you heard about a R-O Firing Pin ?

Later,
Charlie-Painter777