Some of my old hammer doubles have lots of pitting. I did do some measurement to determine average wall thicknesses and some sort-of measurements on the deepest pitts. From a shooter's perspective, these barrels shoot quite nice patterns. Actually, the most pitted set of barrels shoots some of the most even but tight patterns of any of my doubles.
What I do with 16s is use a 12 gauge Foster slug to actually slug the bores at 10 cm increments and then measure OD at those same distances. Gives a good average, apparent wall thickness, on assumption that bores and exteriors are concentric. So far, I have found that ALL of my nice old shooters have been reamed but still have apparent average wall thickness that are 0,035 inches or more. These are nearly all guns that have been heavily used, so, no surprise they have been reamed at least once.
I have quit worrying about pitting making them hard to clean. I do sort of "condition" pitted barrels with fine emery paper, which seems to remove jagged edges on the pitting. Then, I just clean normally, with oooo steel wool on brass brush, and then spray RemOil down the barrels and let them stand vertically for an hour or two. Then wipe with wads of kitchen paper towel, which removes the many flecks of powder fouling that RemOils floats to surface.
These guns have been fired many hundreds of rounds since I got them, one maybe over one thousand. No problems with low pressure target loads or many fewer low pressure hunting loads. I shoot few SAMMI spec load in these guns, usually only to get hulls for reloading.
Niklas
