I find that there is alot of variation in guns, chamber length, and powder and case capacity. Reloading books just give you a place to start at. Like yesterday I was loading .222 remington. The book said that I could expect 3100 fps from 20 grain of powder and I only had 2254 on my chronograph. That said if someone showed me a load that was clearly over the book I would start lower with the same ingredients and work my way up.

So basically if I had no pressure signs I would shoot the same case with that load in it to see how long it took for the case to hit maximum overall length. Often times you won't get pressure signs for the first time that you fire a hot load in a case. Then after like 4 shots it starts to show pressure signs. If you had a chronograph that would tell you even more.