Question about advertised FPS and RL FPS

[leo158]

I am waiting to get my hands on a 17 hornet when ever they get out. Now I was just looking on reloading center (http://data.hodgdon.com/cartridge_load.asp)
They had one load that was close to factory fps and all the rest was way short of the advertised 3600 fps claims. I have even read where they used chronos and got the 3600+fps from factory hornady ammo? Why do all the RL suggestions fall way short of the factory 3600 FPS rnds? Just trying to figure out this new hobby of mine. Thanks ,Dan

[thomae]

What was the barrel length used to get the advertised FPS? What brass, bullet, seating length, distance from lands, temperature, etc... ?
All those variables can make a difference.

Generally I use advertised velocities as a guideline (i.e., "this configuration should be faster than that load.") and don't expect my real life velocities to actually match advertised specs.

Reloading manuals are generally conservative in their max loads because they don't want anything dangerous to happen to a reloader/shooter who is following their recipes. It's a liability thing. Some people safely load over the suggested max loads in the book because they have the knowledge, skills and experience to do so while still being safe.

[308law]

Hornady has also been playing with their loading methods for the last couple of years and have come up with some "secret" methods of blending powders and getting more powder into a case than would be possible with a drop funnel. This is how they have gotten some of their light magnum loads and some of the other high velocity loads that are hard to duplicate without getting high pressure signs.