I have my Grandfather's F grade, 15xxx range, and it is much like yours. Also a pivot lever.
battle, that is a beauty! My 16 F has birds and is an xx frame gun.
I have seen a thumb push F grade that had only line engraving & my early E SN 10,515 has only scroll, no dogs or game. I believe these dogs were the earliest Upgrade to the F engraving, with most later one having the birds of various kinds.
As to the XX frame, I could be wrong on this as have not had opportunity for taking a lot of measurements. I do believe though that firing pin spacings varied according to wt of bbls, but that the determining factor for an XX frame was the width of the bar. The bars on all I have measured taper slightly, growing wider going forward with max width being just where the contouring starts. I have 12ga's from 6½ lbs to 8 lbs with about three different pin hole spacings but all have the same width bar (none XX marked). The above mentioned E is a 10lb 10ga & has a wider bar but no special marking, while my 16ga XX marked H has a narrower bar but weighs 6 3/4 lbs, more than my lightest non XX 12ga.
This gun going to require much work. The ribs are loose and a crack in the wrist. Also someone carved there initials into the stock. I need suggestions on how to repair the initials, I'm sure wood won't be raised in this area. Also the ribs are partially off from the muzzle, how can I remove them? Just apply a torch?
Just saw a 12 ga F grade at the Chantilly show this weekend. It had very similar engraving as yours. If I am remembering correctly, the dog on the left side was flushing a bird, and on the right side the dog has a bird in the mouth. The engraving was very well done, the fine lines were impressive, at least in my uneducated opinion.
For such an anti-gun state, we seem to have quite a number of NJmembers here!
NJdblgun, did you come by our table to visit? Tell us what you bought. I did not buy a Lefever at the show. Bought a nice early A Grade Fox and a Springfield sporter by an unidentified maker but nice. Bill Murphy