Home Forums Reloading Big Game Rifles General reloading question - pressure, velocity?

I've had my reloading setup now for about 4-5 yrs but really been getting more into it as a hobby the last couple of years. I've read on here higher velocity in general means higher pressure. I've also read that loading to the lands increases pressure and loading further off the lands will reduce pressure.

I generally load to the lands when possible which leads me to loads that are longer than book length. I've noticed that on these loads with less bullet seated into the cartridge, I seem to need more powder to get close to book velocities. When I find a good load at a reasonable velocity, I start messing with seating depth to see if I can improve on it. Since I'm already at the lands, the only direction to go is seating the bullet deeper into the case. I'm usually seeing my velocity go up slightly with each load as I seat it deeper, which would lead me to think I'm getting higher pressure.

However, as I seat it deeper in the case, the bullet is getting farther from the lands. This, according to my reading, should be decreasing pressure and therefore velocity.

Am I reading something wrong somewhere or what? What increases pressure more - seating deeper into the case or further out to the lands?

For how many shots are you chronographing your speeds?

In most cases I've generally found seating up to 0.15 or a little more deeply really didn't make any difference to speed, vs being only .020 to 0.030 off the lands.

Here is some info for you.
http://www.hornady.com/ballistics-resource/internal

the pressure spike from the bullet contacting the lands does not seem to come into play until the bullet is seated hard into the lands, while the reduction in capacity is linear (or at least predictable)...

Weatherby used freebore to reduce pressure. Then he increased powder to take advantage of the lower pressure to increase velocity. When you seat the bullet deeper in the case you give it a little jump before it starts building pressure, thus a slight velocity increase.