Many years ago I purchased a 12 gauge twist barrel H grade Lefever. 14" from the breech the left barrel had a crack in it. The crack followed a weld line, thus spirally. Appearance was that it had likely been hit on some sharp cornered object causing the break & subsequently fired.
One side was pushed inward while the other side was flared outward, leaving a large enough gap you could look through it & see the opposite inner bore wall. Bore was very badly pitted. I put my expanding dent plug under it & closed up the gap until it was very hard to see. After taping up the badly broken stock I placed it in "Ye Old Firestone Proof Chamber" & proceeded to fire it.
Firing was done remotely from behind a "Large" tree. I began with several factory Shur Shot loads of 3 1/4 DE 1 1/8 oz shot. I then went to several Factory Express 3 3/4 DE-1 1/4 oz loads. This was followed by a couple of ! 3/8 oz handloads. None of these opened that crack at all, nor even left a sooty smear on the outside of the barrel.
Unless one knew it was there & where to look it is "Extremely Doubtful" one would see it at all if looking this old gun over. Either the Gasoline, Alka-Seltzer or Magna-Flux tests would of course reveal it.
