Well, We discussed how each publisher of these manuals gets their data. By testing stuff in a controlled environment, using pressure testing equipment. And how their testing may be done via a firearm, or a universal receiver.
That's the beginning of the variables.
In general,, the best way to prevent problems,, is to study several manuals,, taking care to see HOW the company got the results, and what components they used. Then cross reference each part of the data to see what will provide the necessary results.
Example;
His load was selected by studying which powders many competitors have chosen for that caliber. TiteGroup.
His load was also selected by testing different bullet weights, and different bullets from different manufacturers but with the same weight.
His load was assembled by looking at the POTENTIAL velocity that would achieve the necessary PF he was seeking. He loaded several test loads,, that were ALL well within the parameters of all the manuals.
Then we chronoed each load, and tested for accuracy, felt recoil, and observed each empty casing for any signs of potential pressure issues. (I don't have pressure testing equipment.)
He then chose a few loads,, and began re-testing things & worked a few variables. Minor powder weight changes, and bullet seating depth. And all of this was done by staying well within the parameters of the manuals. No loads were at the bottom of the charts. No loads were at the top of the charts.
We found that about (3) different loads were quite good in his gun, and provided what he was seeking. An accurate load, mild recoil, and hit the PF level he was seeking.
So, how do we load to prevent potential detonations?
Staying well within the parameters of published data in known manuals.
Making sure each load is built where a double charge would overfill the case, making him aware of a problem. His Dillon has a "Powder check" die in it. If the level is off,, the alarm sounds off. I'm a big believer in the powder check die in a progressive press. A charge that's too light, or too much causes it to sound off.
And by assembling the ammo to where the bullets are also within the parameters of the manuals.
Basically, staying well within the manuals,, And having things in place to prevent over or undercharging a case.
Oh, and lastly,, each & every round is tested in a chamber check gauge. If there's an anomaly in the assembled round,, it will appear there.
Having followed these procedures for decades,, I've assembled well over 150,000 rounds of competition ammo for USPSA. And before I got my first Dillon,, (which I also bought the powder check die at the same time,) I would visually inspect the levels of powder in all cases to assure all were of the same volume.
I still do that for calibers that are not loaded on my Dillon.
Accuracy is the final authority for what I seek in my ammo. But I will not seek accuracy by pushing the limits of any combo of components. I choose to change components to build a load if I see any sign of approaching too much power.
Long ago,, I seriously studied a lot of detailed technical data written by Rick Jamison in Shooting Times. His column,, "Precision Reloading" helped me understand a lot about how to assemble good quality handloads. Rick also had pressure testing equipment to check his work. I also have met Rick,, and we've enjoyed discussions on handloading.
One big thing he found,, and stressed is to try & find a good balance of components. And most of his work revolved around rifles. But he also stressed that he seemed to find the most accurate AND efficient ammo where the balance of components once combined allowed for a fill of the case with powder,, that once the bullet was seated, the bullet base touched the powder. And of course,, that was also by following the manuals.
His words were proven true to me when I saw the development of Trail Boss powder to prevent SASS folks from loads that didn't fill a case enough.
And there is a difference I wish to point out.
There is a difference in a reloader & a handloader.
A reloader just follows what he finds in a book & doesn't study to see if it's the best.
A handloader is heavily involved in the serious study of HOW to assemble the best, balanced loads in any firearm SAFELY!
BTW,, even after almost 48 years of reloading then handloading experience,, I STILL study & learn as much as I can. Plus a study in explosives & burn rates hasn't hurt either.