I got a small flashlight, the size of 1/2 a AAA battery, stuck some opaque plastic over the lens and slid it down the bore facing toward the muzzle..
Gives not a bad initial look.
As others have said the cheap borescope type things you can send down the bore work well too.
Make sure you get one with an angled mirror attachment to get a good look sideways as it goes down.
Be warned, looking through these makes things look far worse than they probably would to the naked eye.
Mines certainly got some pitting here and there, but the breech area was pretty good. Bear in mind you have one pit each side that goes clean through the barrel :-)
I shoot mine with conservative loads of Swiss 2F without issue, but that's a call you have to make.
There's some good info on original muzzle-loaders here:
http://www.cablesfarm.co.uk/a-beginners-...ders/#more-1630GDU
