... Heat checking in the bore ("expansion cracks" by another name) in the throat area of a used barrel is a real enough phenomenon, and observable through a borescope. It is usually in a checkerboard pattern, or "alligator skin" - an array of fine cracks due to the rapid heating and cooling (and associated expansion and contraction) of the bore surface.
Dan-
Thanks for your post. I've read about "expansion cracks" in another context of barrel steel, where the discussion and description was clearly fanciful. I was unaware of the term's use in connection with bore and particularly throat erosion.
Back to the books for me. (A recent Australian publication on bore erosion:
[color:#0000FF]Understanding and Predicting Gun Barrel Erosion[/color].)
--Bob
