I haven't measured my brass just load it.
You just hit on something that probably 99% of shooters might never realize.
There are specs on case trim length, and then there are specific dimensions of a particular rifle.
The published specs are simply GUIDELINES that are supposed to be safe in ANY rifle made to the guidelines.
Now, MOST factory chambers will safely take cartridge cases considerably longer than the published specs.
I call these chambers "lawyer approved" as they are made longer to help keep pressures lower.
The unfortunate side-effect is reduced accuracy potential.
Sinclair sells a simple tool to measure YOUR chamber length.
Once you determine what your rifle can take, trim 0.010" to 0.015" shorter and be done with it.
If you have a chamber that's 0.060" longer than spec, I doubt you would ever need to trim your cases before they wear out.
That is post number 8 here. www.calguns.net/calgun...hp?t=95166