pressure/velocity change from shortening c.o.l.

[saskgunowner101]

I recently started reloading for the 9.3x62 and was curious about a couple things. I'm running data from Hodgdons site, pretty much starting loads or a grain over. 285 grain Privi bullet, with 55 grain Varget, CCI 200's large primer, Graf brass.I kept the c.o.l. longer than the recipe called for running at 3.275 or so instead of the 3.225 listed.

What little ammo I had put over a buddies chronograph seems to indicate I was bang on or a touch higher for stated velocities. I did not crimp these loads, as I would if used for hunting.

I'm wondering with all things equal, would seating them .05 deeper to 3.225 cut the velocity and raise pressure?? Raise velocity and increase pressure?? Any thoughts on this appreciated.

 

[B]

That is pretty hard to tell. Different powders and would give different results. Some powders have funky pressure curves. I imagine placing it at a shorter COL would raise pressure at the least. Whether that would be something to worry about is beyond my knowledge. Raising pressure does not give always give you more speed BTW.

 

[Eagleye]

Often depends on how close you are to the rifling initially. If you are tucked right up to the lands, pressures may actually be higher than if you seat it a bit shorter. Reducing powder space is of concern to some, but in my personal experience, I have loaded many loads that result in a heavily compressed charge, and have yet to see any indications that this caused higher than normal pressures, provided the powder used is suitable at the stated charge weights. It is a very complex issue, and watching for any excess pressure signs very carefully when you change seating depth is always discreet. Regards, Eagleye.