Originally Posted by Airborne1101
I research multiple manuals, start loads well below max shown and work up or down in some cases
AIRBORNE......All the Way!!
I assume you are refering to bottleneck rifle loads? Straight wall Pistols are a different animal when it comes to COAL.
Do not go below Min published charge. This can be just as dangerous as going above Max. There is a Min for a reason. Some powders like H 4895 work well with reduced loads, but there is data to support this.
If you seat the bullet to a COL greater than the COL of the base line, the pressure will go down. The pressure will go up if you seat the bullet deeper (less COL).
This is not necessarily true. There is countless studies that show in a bottle neck rifle cartridge pressures usually go down when the bullet is seated deaper, not up. Here is one such study by Barnes. Scroll down to "From the Lab"
Here is what Accurate Powders says about COAL.
SPECIAL NOTE ON CARTRIDGE OVERALL LENGTH “COL”
It is important to note that the SAAMI “COL” values are for the firearms and ammunition manufacturers industry and must
be seen as a guideline only.
The individual reloader is free to adjust this dimension to suit their particular firearm-component-weapon combination.
This parameter is determined by various dimensions such as 1) magazine length (space), 2) freebore-lead dimensions of
the barrel, 3) ogive or profile of the projectile and 4) position of cannelure or crimp groove.