Pressure Signs . . . . and what to look for

Notice the difference in how flat these primers are.

Examining the flatness of your fired primers is the best way to read chamber pressure. It's important to keep an eye on this when you're reloading. These 4 fired cases clearly show the different degrees of chamber pressure, and this is an accurate representation when reloading any caliber. If you pay close attention to your fired cases, and you slowly work your way to hotter loads, you'll avoid seeing any of the "serious" pressure signs.

Very mild load (this is too mild).
Mild load.

This is an ideal load (could go just a bit hotter).

Absolute Maximum load (approach this pressure very carefully).

Some brands of primers have a noticeably harder cup than others. This difference in hardness can cause a slight variation in your pressure readings. Seating bullets too short or too long will affect chamber pressure considerably, and some types of powder will increase pressure as the outside temperature increases. When you develop maximum loads in the winter, beware of the pressure increase when using those handloads in the heat of summer.