Interesting question as to what that analysis would have been for a 105 mm round. A primer would only ignite the propelling charge which is violent in the chamber only because it is confined. When you burn off excess charges they create a substantial but non-explosive fireball. If a primer went off outside the tube I would presume that once the ignition started there would be a point of pressure that would blow the casing away from the projectile and then end up with a Roman candle-like event rather than a proper explosion. ??? The projectile ought to be unaffected. It's tough enough to withstand the full explosion in the chamber so should easily withstand a squib outside of it.
Regardless, by then it would have been too late to run of course, but nonetheless, I would have been running right beside you and everybody else anyway. ;D
:cheers: