I am not new to reloading but I don't have much experience developing loads either. Apparently both my savage predator in .223 and my Winchester .375HH will shoot pretty much anything you put thru them.

I have a new Savage Weather warrior in 30-06. I worked up some sample loads.

once fired remington brass
Winchester WLR primers
Nosler partitions in 165gr.
And I started with 55 grains of IMR-4350 and worked up to max in .5 gr. increments
Bullet seated .06" of lands

A thunder storm interrupted my session and I did not get to shoot the max group. But it looked like the best group was about 1.125". The loads seemed to be stringing in a horizontal line. The next day I went and shot the max load. It was around 2" and in triangular pattern.
So I say to myself I need to try the 55.5 grain load again as it seemed the best. Now its about 2 inches also.

The only thing I changed was the length of the cases. Before I did not trim them all to the same length. (just under minimum) The past couple of groups I have trimmed to the full range of a Lee hand trimmer. Probably .005"- .007" shorter.

Could this small change in length have that effect?

Trimming the brass shouldn't have much effect. You probably should try some different combinations of powder and bullets. Rifles are individuals and just because a particular combination works in most rifles, yours may not like it.

quote:

Could this small change in length have that effect?

should make no difference. seating the bullet shorter or longer will make a diffrence

Try a seating depth of 30 thou - 0.030 inch. That could improve your groups. Your magazine should take that.

Also try H4350 and other cup & core bullets.

Your barrel might prefer 150gr or 180 gr bullets. Each barrel seems to have its own sweet bullet.

BTW 1.125inch is a very good group for a hunting rifle.