Mine has the "Wm. Evans (From Purdey's)" on one barrel.

I must confess to not having worked up a good load for it. I slugged the barrels and they are 0.3665 inch. Probably the ideal size for the original bullet reputed to be 0.367 inch. A tad over sized for today's 0.366 bullets. I have some 285 grain bullets of German make and recently some 300 grain soft points from a US custom maker.

Do you find you can get both barrels together with lighter bullets?

I'd be interested to hear what you are using for loads.

I've been modifiying 9.3x74R brass. I find Bertram brass to be hopeless.

It's odd that no decent 400-360 brass is avaiable as it's actally a fairly common caliber. Purdey states that it was their most popular caliber in its class at the time. There must be a 100 400-360s around for every 600 Nitro but you can buy 600 Nitro brass.

One odd incident. I had a round in which the primer went off but the powder didn't. The primer drove the bullet about six inches up the barrel. This allowed the powder to spill out of the case when I opened the action. I found that I could not close the action so long as there was even one flake of powder left in it. I won't list the load since you wouldn't want it when facing down an enraged hog.