I am relatively new to reloading. This is my 4th load to develope and the first one to develop by myself. I have been working on a load for my 300 win mag. I am using 168 gr ttsx bt. I worked up loads using IRM 4350 and IMR 4831. I was able to get pretty good 100 yrd groups with both. Both happened to be a relatively the same velocity, 3100 fps. My guestion is, is the grouping better at acertian velocities a result of seating depth? If I changed the depth may my group tighten at high velocities? Any help would be greatly appreciated.

Jason Badley

changing the seating depth just changes the jump from your case to it's engagement of the rifling.
if your rifle has a sweet spot for the jump.
you can burn about any powder behind the bullet and keep your accuracy.
velocity can make a difference in accuracy also.
lok up audettes ladder method for a better idea.
changing the seating depths,incremental powder changes and primer swaps is part of tuning a load for your rifle.

Lamar,
Thanks for the response. Thanks for mentioning the audettes ladder method, sounds really interesting. Wish I would ave started with it. I have shot about 80 rounds now working on this load. I have worked up the ladder shooting gropus of 4 with charge weights going up .5 grains with both powders. And with both powders, my best grouping came at the 3100 fps velocity (70 grs of IMR4350 and 72 grs of IMR4831). I shot further up the ladder with out any signs of pressure and achieved greater velocities. But my grouping spread out towards the inch range. I was just wondering if it was worth trying to gain the extra 125 to 150 fps and expect to be able to shrink the grouping back down. This is a hunting rifle and doubt I shoot anything much ove 400 yards, so I probably should just be happy with what I got and move on.

your groups might come back down in size.
but i'd go with the fuller case of powder.
back it down just a tad and try the seating depth changes.
then maybe a primer test.
i have opened and shrunk groups with just primer changes.
sometimes no change whatsoever.
but when components are hard to find a back-up plan is nice.