Jones, I guess I didn't read your description close enough the first time because your clearly said it had the GRRW stamp. Here is a pic of another GRRW Hawken I have that has the later stamp like yours. Note the serial number on this one is 619. The serial number is also on the stock in the barrel channel.
A couple more pics of the rifle:
This rifle has a Ron Long lock and triggers. This lock is hand engraved while the engraving on the earlier rifle was part of the casting. The barrel is 36" long and 1-1/8" across the flats, no taper. Makes for a heavy rifle. The barrel on the earlier GRRW Hawken is a little over 32" long and 1" across the flats and about 2 lbs lighter. It will be my hunting rifle.
Factory made GRRW rifles could be called semi-custom. Their patterns appear to have changed some over time, but you could order an early J&S Hawken style or a later S Hawken style, in half-stock or full-stock. In fact, you could special order different locks such as Long's or Griffith Tool Co. and fancy wood, thus offering several custom features.
As Powderburner said, they also made half-stock and full-stock Leman's and a Poor Boy. Most of their guns were also available in kits.
Here are some pics from a 1978 vintage brochure and a 1980 brochure.
1980
I ordered three kits from them between 1978 and 1980. One kit, a full-stock Leman, I finished back then, the other two, a full-stock flinter Hawken and a half-stock Hawken, I'm still working on. The Leman full-stock is a handy rifle with a 30" barrel. I used it for hunting last year, and it was a pleasure to carry. It lives up to the accuracy reputation of the GRRW barrels, too.