It isn't too hard to calculate what the static equivalent force on each bolt would be in lbs, then the stress in psi, if you start with an assumed maximum chamber pressure, let's say 10,000 psi just for illustration. Multiply it by the area of the "cap" inside that's exposed to that pressure, for bowling ball bore dia., somewhere around 60 square inches, so total instantaneous force on the cap is 600,000 lbs. when fired. Just divide that by the number of bolts and you get the average force tending to pull each bolt apart lengthwise. Divide that by the cross-sectional area of a bolt and you have the stress in PSI on each bolt, average. Compare that to the rating of whatever grade bolt he's using. That isn't a precise method but if the stress that one shot puts on a bolt is way over its design tensile strength, you are asking for trouble either on the first shot or a few shots later...
A failure may not be as lethal as a tube actually bursting, but any rupture of the system at ballistic pressures is bound to be dramatic if not dangerous to bystanders.
