The rifle is quite nice.
According to my ink-signed Westley Richards documents, it was delivered to the New Bond Street shop in 1864
At some time later it went through the shop of F.Fletcher of Gloucester, this is advertised on the rib extension.
Ever hear of Fletcher?
Evidently, S Baker thought very highly of Fletcher and spoke to that effect on a few of his books. S Baker's favorite rifle (the one that went to bed with him every night) was built by Fletcher of Gloucester.

The chambers are long, to the tune of 3" long.
2-3/4" Chedite, Federal, and Winchester hulls all fit in there just fine.
Tom Armbrust did a pressure/velocity test for me in winter with Seven drams weight Swiss 2f Black in Chedite Paper Hulls
.670 Roundball
card wad
1/8" lubed felt wad
65lb seating pressure
665 bore (his pressure barrel, these grooves are a bit bigger, but more on that later)

Two shots

13,550 psi
1784 fpsMV
1780 fpsMV

When I'd called him to ask if he'd run this hot of 16bore rifle loads before, he told me that he hadn't, but that he was thrilled at the idea so I shipped him roundball and hulls.

The day he tested the loads, it was all he could do to get back to his kitchen to call me, still laughing!
His first comment was that there was 'Lots of Smoke!', furthermore, excellent velocity and essentially no indication of pressure sign on the french paper hulls.
If it weren't for the piercing from the chamber tranducer, Tom reported that the hulls could be reloaded 'numerous times'

I don't know if this rifle will regulate with seven drams of black.
If it does... I'd be just fine with that.
The rifle weighs right about 12lbs, I'll get it on an accurate scale later for a better number.
The action is absolutely solid. It locks tight as can be without being stiff in function (freakin vault), there's two bites under the flats and a crossbolt through the rib extension.
The action itself appears to be 10-bore size, with the action balls cropped close to the head.
This thing is solid and massive.

The wood is marvelous.
In the words of an 'old retired stock finisher for the London trade' this wood is to die for.
It passed through his hands during a 'little weekend at the spa' on it's way to me here in California.

Hopefully I'll get some time together this weekend to run some black and roundball through it at the ranch.
You guys cross a finger for me.

Until then Peter get your 12bore ready for a walk through the Northern woods this fall, our rifles will definitely do against coastal black bear!

Cheers
Tinker