Toebako, that is a very interesting gun your buddy has there. A sidelock with London proof marks is usually enough to capture any gun nut's attention. The barrels are true Damascus, not twist or stub. The walnut is not too bad (has the chequering been recut?) and overall the gun does not look like it has been monkeyed with too much.
This is not a "best" gun however, rather it is an economy model. The evidence for this is the sparse engraving, and the presence of back action (as opposed to bar action) locks without safety sears.
It is those very locks which are so interesting. They are not of usual construction. Your last photo clearly shows the two screws which hold the lock plates on, and the large pin which is the tumbler axis. Also visible is the small pin at the rear of the lock plate which is the usual position of the mainspring anchor. There are two other small pins, below and on either side of the tumbler axis. They are the interesting part. There are usually three pins instead of just two (more, if they were expensive locks). These should be the bridle pins. Having just two pins, and having them located at the bottom of the lock plate only, is not the most common method of construction.
For all the world the locks look like the William Baker patent coil spring locks of 1902. However, the old black powder proof and Damascus barrels make me believe that the gun is more like 1880-ish vintage than 1902. I would love to see the inside of those locks.
You will get a chance to see the hidden side of the locks if buddy chooses to repair the firing pin. Fortunately, the firing pins of sidelock actions are usually separate pieces, not built integrally into the tumblers (hammers) like many boxlocks. The screw at the front of the action just above the lock plate should be the firing pin retaining screw. Remove the locks, take out the good firing pin and have a gunsmith or good machinist make a couple of new ones. If you do that, please take a picture or two of the inside of the locks. Note that there may be other problems with the afflicted lock, but there will be no way to tell until the locks are pulled.
NOTE: If he is going to attempt this himself,please take the time to grind a screwdriver to the proper size, and try not to do any further damage to the screw heads. It is really easy to bugger up old English screw heads, and nearly impossible to fix them, so be careful!
As I said, an interesting gun and while it looks well used, it also looks largely intact and (if repaired) quite shootable with black powder loads. In its present condition (broken firing pin and possibly other, as yet unknown damage) no one will give him much for it. They would be taking a risk, gambling on what it would cost to fix. In a repaired, shootable state (ie. no play in the barrel bolting, no dings in the barrels) but not refinished, the gun would be attractive to many shooters. London proven sidelock SxS's are not something you see every day, after all. In repaired, shootable condition I'd ask $1,200 for it and bide my time. Just my opinion, though, I advise you to get more.
Sharptail
