Wonko;
You don't always have to try & Show off your "Superior Intelligence" by trying to show every on UP.
I well know that it has been many many years since a flat bar was rolled into a tube with weld seam down the side to form a gun barrel.
How-so-ever an internal flaw on the inside of a piece of steel can be drawn out in the forming. This in the trade is known as a "SEAM". There are any number of recorded instances where such seams have resulted in burst barrels. "IF" however this were the only cause a ring bulge would not be present, thus my mention of the possible combination of a barrel fault which was holding up until stressed by the obstructional pressure.
When you don't know what you are talking about its always better to ask Questions than just go Belittling Everyone.
