Some barrels just seem to shoot faster, and therefore show pressure signs with lighter loads.

You do not say if you get higher velocities along with your apparent pressure signs, but you should.

Incidentally, in comparing primer flattening, you must be comparing the same primer brand. CCI, for instance, sometimes flattens more than other brands.

The only way you can really know that you are getting higher pressure is to chronograph the loads, and measure case head expansion.

I have a .270 which also shows pressure, but velocity is also high, and most factory ammo shoots about 100 fps faster than it is supposed to.

I agree with the above post about Ruger barrels. They are not known for consistency.
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