I am not convinced that these incidents are all results of a "short start," and I recognize that is not what you said. Short Starting can certainly cause major problems.
I have in my mind that some of these blown barrels are being caused by the projectile - projectile sabot combination and of course the powder charge.
We all know that the energy necessary to start an object at rest is greater than the energy needed to start a moving object, additionally the heavier the projectile the more energy needed. The smaller the barrel the quicker the build up of energy because of the smaller chamber. YET, I do see people standing on, hammering, and generally struggling to get their projectile down the barrel. Something, pressure, has to start that projectile going the other way and again the size of the chamber has a huge effect on the build up of pressure. Keep in mind the quicker the projectile moves up the barrel the larger the comustion chamber becomes and the quicker the pressure is reduced. (hence the difference
in maximum loads for a a 50 vs. a 54)
I THINK, it is important that you choose a projectile sytem that goes down the barrel with a moderate amount of pressure the first time the 5th and/or the 10th time. I choose to load bullet/sabot combination that i can push down the barrel to the muzzle with my thumb (don't have any guns with QLA's) - I do not use a short starter at all. This is my standard for all of my proven rounds. If I use a new new projectile - projectile sabot combination I reduce the charge until I know the pressure the bullet combination requires to go down the barrel.
Some will say that I am loosing pressure because of the loose projectile. (now mind you it is not loose it will not come off the powder, but I didn't pound it down the barrel) I have found when shooting this system over a chrono I get very consistent velocities and in the range you would expect with 100 grains of t7 - 2f or 3f.
If you look at the Savage that Toby Bridges blew up, I can't imagine that he short started a bullet.
As they say this is just my 2 cents worth....