My unmessed with Inland in an IO oval cut, highwood stock has the P in the circle on the bottom of the pistol grip.
My "messed with some" 476K Inland with the same stock as imarangemaster's has the circled P. - Bob
The P proof on the bottom of the grip was not used long after the type 2 stock was in general use. The P on the barrel was the main proof mark so anything to save time,effort and of course cost was adopted when ever possible.