I believe the safest way to reload is to regard Velocity, Powder charge, and even unreliable "pressure signs" as stop signs to back away from.
Chronograph loads as you work your way up and if you start exceeding normal velocities for a given caliber/bullet weight/powder combination you are likely to be exceeding normal pressures.
If you start going past maximum loads in reliable pressure tested manuals you are likely also most likely exceeding their pressures.
Lastly if your rifle is showing obvious flattened primers, sticky bolt lift, loose primers or over expanded case heads obviously something is wrong! You usually will run into the one of the first two first.
I also like to look at several manuals. If one manual has a powder charge or velocity way different than the others I look at it very skeptically. Some manuals AREN'T pressure tested and are less reliable than ones that are.
I have a round I load for in 3 different rifles. In ALL three rifles a load 2.5grs UNDER their maximum listed load I get over 200fps ABOVE their listed max velocity! Obviously I'm not going to try and load anywhere near their max load. It also makes me VERY skeptical about some of their other loads since they are by far the highest on several powders and I know that they don't actually pressure test their loads.
I really think they are too many reloaders that think as long as they aren't popping primers and don't have to use a lead hammer to open their bolt they are within safe pressure limits. I talked to too many that think they are somehow magically able to load the same components 200-300fps faster than everybody else without exceeding pressures they should. They are wrong. :-/
