Using a wall thickness gauge is not difficult, but takes time,
and is a 2 man job; one manipulating the gauge and the other to rotate the barrels (because of eccentricity) and record results.
One word of warning.
I've measured refinished barrels with bores at the expected factory dimensions, but the exterior of one 16g barrel had been filed to remove pits, and the wall thickness was
.016”, 14” from the breech. It had survived 250 2 1/2” Polywad Spred-R shells, 100 2 1/2” 7/8 oz. at 1145 fps. (about 8000 psi) loads, and 2 cases (500 shells) of 2 1/2” RST 3/4 oz. at 1100 fps (4,600 psi per RST) without rupture or dimensional changes.
And at the risk of repeating myself
a dealer reporting "MWT is ____" is totally inadequate