Wes,
There are FAR to many stupidities and superstitions constantly being thrown around as fact.
Here is the reality, and here is what you need to know.
When it was decided that blowing things up on guesses want good enough they invented very carefully calibrated Lead Crushers, reporting LUP. As operating pressures rose, they were no longer accurate. So they moved to copper crushers, CUP. Again pressures rose, and in a very well publicized set of tests, it was shown that the same reference load reported pressures differing by 20,000 psi. So the world agreed that over about 45,000psi, copper crushers are not accurate. So we have moved on to Strain guage systems.
Since WWII there is NO cartridge company that publishes the alloy, or heat treatment specs of their brass. The last published alloy from Olin(who no longer makes any) was C260, which was spec'd to a tensile strength of @ 85,000 psi. So when you could measure brass expansion, you knew you were around 85,000 psi.
So, you have brass from an unknown alloy, primers from an unknown alloy. AND we know copper crushers can't accurately report current operating pressures. So why magically primers and brass are supposed to be accurate at Pressure reporting, is not only wrong; it needs to stop being repeated.
So what are you supposed to do? Buy a CHRONOGRAPH!!
Book data is all Pressure tested in SAAMI minimum spec equipment. Powders have a burning rate variation of around 10%. So ignore the specific grains listed, watch the velocity! Your production firearm has loser tolerances than the pressure testing. So you will never have identical velocities at the same Pressure. The difference is in the powders burning rate. Start at the start and work up under the chrono the whole time. When you see the difference in velocity change it exceed listed numbers, you know you have gone over Pressure.
A few other things to remember is that factory ammo (except Nosler) does NOT use canister grade powder (which is what we can buy).
Watch velocities. OR if you really want to know your specific rifle pressure, buy a Pressure Trace from RSI.
It is a strain guage system that allows you to see what is happening in YOUR rifle. Costs about the same as your rifle. Let's you see burning curves and Pressure spikes like these.
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