What do the records say...

[edgarspencer]

Rick, It doesn't actually say Grade 0, merely Plain Twist, but many Grade 1 hammer guns had Twist as well as Laminated barrels. Who knows what grade it is till we see it. It has to be one of the highest SN# hammer guns, and most likely on an 0 frame. Certainly, I've never seen one so high, but have heard of special order hammer guns made in the early '20s. Sure hope the OP gets some pics. I can't wait!

[John Cinkoske]

"Parker Brothers Makers, Meriden Conn Parker Steel".
Is 'Parker Steel' a twist or laminate? Doesn't look like any I've seen.
Is there any factory reason it would have gorilla mainsprings? It's a bear to cock this one.
The owner calls it a P grade 'Fluted Frame'?
I'll not see him for awhile, but I will get photos.

[edgarspencer]

Parker Steel is a designation for the barrel steel used on the PH, and PHE. These Grade One guns also used Twist Steel. However, there are also Grade One hammer guns, and that's what the 'book' indicates 171718 to be.
Hammer springs on Parker locks are very strong, right out of the gate. I had an Austrian gunsmith friend of mine rework the springs in one of my guns and now they are very civilized, and I can cock both with my thumb on the way to the shoulder.

I'm wondering about the reference to 'flutes' as this usually pertains to the sculpting of the hammerless gun frame. The flutes on either side of the frame were changed from a longer flute to a short flute at about the same time as the safety button was changed.
The Serialization book has been known to contain errors, so you've got me wondering whether we're talking about a grade one hammer gun, or a grade one, P grade hammerless gun. The book says "PT, meaning barrel steel of plain twist, T, meaning Top lever Hammer gun, 0, meaning no options, such as special fore end, C, meaning capped pistol grip stock, 20, the gauge, 26, meaning the barrel length. Does this sound familiar?