After shooting 30 rounds in my 7.7 I checked all the cases and they looked perfect. But I noticed that the ones that used CCI-250 primers left a small ridge that could be felt with a finger nail. All the others , Fed, Win, and CCI-200 were still deep in the pocket. The spent 250 primers were flattened out more tha tthe others. The load was 42 grains IMR-4064 and shot 1/2 groups at 100 yards with mild recoil. Any ideas on this ridge?

The CCI's deform easier than the rest (some would say there "softer"), so they show "pressure" sooner (one of the problems with the "primer signs of pressure" is how much different brands/lots of various primers will extrude at the same level of pressure)

Another variable in the "ridge" would be the radius on the firing pin nose, and the pin clearence in the bolt face. With a sloppy pin you can get a ridge at quite low pressure.
All the pressure signs are not "measurements" and never will be. They are warnings that you may be approaching a yeild point. Time to thing about what you are doing.
Good Luck!

cci250 are magnum primers the others are standard, It is not a good practice to change components with out reducing the load and working back up,
mag primers are hotter than standard primers.
Dave

I talked to a fellow who reloads and shoot a lot and he said about the same thing about CCI primers. I hardly if ever use a CCI let alone magnum primer but decided to try in in this load and it worked well with 1/2 groups. And a load of 44 grains, up from the 42 didn't show any differance in the primers or the firing pin hole. (no cratering) But the 44 grain load started to spread out to 3/4. These were some CCI primers I bought a few years ago when the "no primer" scare came along. Understand the hotter magnum primer and going to try 41 grains with it.
Thanks
Bob

Yeah understand abot changing things around. But I have delt with IMR-4064 in quite a few different calibers and knew that the 42 grain load was ok for the 30 caliber, 310 caliber. The primer didn't show any great pressure effects but did flatten out. The case was perfect. Firing pin indention looked gtreat also. Didn't know about the CCI being a bit softer and showing up like this before most others would.
Thanks
Bob

I just wait until the primers start to flatten. If I can't tell the difference between the case and primer, then it is time to reduce some grains.

The CCI did flatten out and the other primers with the same load looked normal. With the flattened CCI the firing pin hole was the same as all the rest. Going to redue the load and see what happens.
Thanks

Primer appearance is not a very reliable means of determining pressure. You can get primer flattening on relatively light loads and excessive headspace.
But a mag primer will generally increase your pressure over a non-mag primed load. You may be comparing apples and oranges. Chroning the load will tell you more.