Thanks everyone for the great responses! Sorry for the slow reply - I've been busy lately. I managed to get to the range and try out loads from 7.0 gr up to 8.4 gr (Longshot powder) with 200 gr hard cast projectiles.

I don't have a chronograph (yet), so I'm not sure how they went velocity-wise. But the casings all seem quite good after firing. The 8.2 gr loads had fired casings roughly the same diameter (top and bottom) as lower loads (around 0.425" to 0.427", with some 0.430" right in the middle), but no "Glock smile" despite using a Glock. My 8.4 gr casings do seem quite a bit larger - about 0.430" to 0.432" around the base, though still no apparent Glock smile nor any permanent mark.

So now I'm wondering about reloading this brass. I assume I should be all good to go reloading the 7.0 gr to 8.2 gr load brass with loads up to 8.2 gr (is that true?), since it seems ok for diameter, length and has no permanent markings. But what about the 8.4 gr load brass? Is it at all safe to reload? Should I reload it only with reduced loads? Would it even be fine reloading at 8.4 gr again?

Thanks so much again everyone - I'm new to (slightly) pushing max load boundaries, so any advice is appreciated (and obviously all risk and responsibility is on me ).

Hi everyone, I've been reloading for a while, but I've never wanted to exceed max load. But now I'm looking to get the most out of my 10mm for bear defense and noticed that often the max load listed for a powder/projectile combination will not get close to the max pressure.

For example, Hodgdon's reloading data (http://www.hodgdonreloading.com/data/pistol) for 10mm, 200 gr shows a max load of 8.2 gr of Longshot, giving a pressure of 35,000 PSI. This is 2,500 PSI below max pressure.
They also show a max load of 5.9 gr for Universal, giving a pressure of 36,900 PSI. This is much higher pressure, though is still 600 PSI below max.

I'm wondering what factors go into deciding the max pressure. I noticed for 800-X, the pressure for the max load is 32,500 PSI - I could imagine that is because it meters poorly, meaning more of a safety factor must be used to ensured that large deviations in 800-X loads still won't go above 37,500 PSI.
Is this the only factor? Is it even a factor? I've also wondered about whether it takes into account if powder would be crushed after a certain number of grains, or perhaps if accuracy would suffer terribly. I'm just struggling to work out why some max loads for some powders are so close to max pressure, while others are far below it.

Does anyone have any insight on this? Is there any reason why one powder at max pressure (even if it's way over max load) would be any more dangerous than another powder at max pressure? Does anyone know what charge weight of Longshot gives close to max pressure?

Thanks!