Again, Graybeard +1
You can see the pressure rise in your primer as shown by the degree of flatness, but you can't tell anything other than the pressure is getting higher. Several reasons for that, but the shortest one is that some primers are 'tougher' than others so it takes more pressure to create 'the same amount of flatness' than say a primer made of softer material. Not wrong, just different. Likewise, some primers are hotter than others, within the same category; ie. standard, magnum, benchrest, etc. All this creates a different picture as you look at the spent primer and try to evaluate the pressure. It's about an excercise in futility.
When the primer falls on the ground as the case is extracted, I consider that a pretty fair sign that things have gone over the top. You really don't need to go there. Sticky extraction has been given as a sign of high pressure, but lots of stuff can cause sticky extraction, including a simple need of a good cleaning.
Best I can offer is get a good manual and read all it's tips for handloading, follow it as a guide to find what your rifle likes for accuracy and realistic performance, then shoot and shoot and learn to read and listen to your rifle - it will talk to you. I for one do not care for the 'get a chronograph and keep your velocity within the scope of the manual' guidance mainly because each rifle is an entity unto itself, which is why none of the manuals agree with each other over powder charge and velocity. You can easily get off course using a 'loose manual' with a 'tight' chambered rifle, and get into an over pressure situation.
Years ago, like a lot of my peers, I hotrodded everything I got my hands on. One rifle in particular, my favorite, has never had a sticky extraction, but...did dump a primer on the ground and the muzzle blast was fierce and the 'sound' was about above my threshold of hearing - with my earmuffs on. Didn't load it that hot any more. Another of my favorites will stick a case in the chamber on a hot day with anywhere near a max manual load. Changed to a powder with less temperature sensitivity and held it down a touch. We have to learn what works and be patient and totally aware of what is going on and stay safe.
We really don't need every ounce of performance that is built into our weapons. It's amazing what a low pressure load will do in the hunting field, if we will learn to shoot our chosen weapon proficiently, and learn to be 'hunters' not just 'shooters'. I've shot enough elk, deer, and antelope under 100 yards to know it can be done, and enough over 250 yards to know I can do that also, but don't need to. As a side benefit, they are a lot easier to find when they are down under 100 yards.
You are on a journey, and it's a great education. Happy handloading.
Regards,
Sweetwater
