Seating Depth

George, seat the bullets very near of not barely touching the lands

Rule of thumb

Horizontal means add more powder

Vertical groups mean adjust your seating depth

Start at the start, bedded action, freefloated barrel

Wind is always a major factor, especially a quartering wind in your face
 
This is occurring with a proven load the last two times I have shot it. Two tight and the third below and off to the side. The rifle as all my rifles are bedded and barrels free floated.

If you are getting two shots and one out in a three shot groups should you seat the bullet longer or shorter?

I should have been more specific, this is a load I worked up a few months ago. I am talking a series of three shot groups not just one. I have shot groups as small as 3/16" and today for six three shot groups it averaged 9/16" for the six groups. It is just a Ruger MKII 243 sporter rifle, the groups all have two touching and one that is below. I know I seated this load at 2.630 instead of the 2.645 that I normally use for the rifle.

 
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George, I would guess that the leade in your barrel has grown a tad bit. Check the OAL and measure with an Ogive gauge.

We call this, "chasing the lands" as the throat wears. I save a bullet and put it in my die box, use that same bullet to measure the leade growth.

Your barrel liked a certain bullet jump...as long as you can maintain that specific seating depth to the lands, your accuracy should be maintained.

As the barrel gets wear, velocity will drop a little. Check the velocity now when it shoots very well, later on when the barrel has some wear, add powder to the charge till you get that
specific velocity back.
 
Originally Posted By: ackleymanGeorge, seat the bullets very near of not barely touching the lands

Rule of thumb

Horizontal means add more powder

Vertical groups mean adjust your seating depth

Start at the start, bedded action, freefloated barrel

Wind is always a major factor, especially a quartering wind in your face

Very good advice
 
While I very much understand the "Rule of Thumb". What if seating the bullets so long that you just turned your repeater into a single shot? Some factory rifles have long leads and short mag box's.
 
With a hunting rifle I start 0.020 off touch. I do a incremental powder test to find 1. A node with minimal vertical dispersion(hopefully .5+ gr with the smaller varmint calibers) 2. I want to find what charge weight pressure starts to show up(or a velocity over book), hopefully I can load to max charge in a couple different load data sources. Then I may adjust seating depth(away from the lands) if I see some shots that don't stay in a group, with hunting rifles for coyote and smaller if the rifle is consistent .75 groups I will try a couple 0.010 jumps to see I there is a change. Otherwise I run with it.
 
I'm having the same problem with working up a load for a 22-250 a recently acquired. I shot some test loads yesterday and would have 2 touching and 1 off. I feel I'm doing my part, although at 56 my eyes aren't what they used to be. Going to experiment with seating depth, using a O.A.L. gauge and started at .020 of lands.
 
Originally Posted By: ackleymanGeorge, seat the bullets very near of not barely touching the lands

Rule of thumb

Horizontal means add more powder

Vertical groups mean adjust your seating depth


Actually this is backwards, I'm sure it was a slip up on Ackleyman's part, as generally he is spot on.

Vertical- powder charge +-
Horizontal- seating depth +-
 
Originally Posted By: BeluebowOriginally Posted By: ackleymanGeorge, seat the bullets very near of not barely touching the lands

Rule of thumb

Horizontal means add more powder

Vertical groups mean adjust your seating depth


Actually this is backwards, I'm sure it was a slip up on Ackleyman's part, as generally he is spot on.

Vertical- powder charge +-
Horizontal- seating depth +-



This
 
Originally Posted By: BEN243Just to clear things up ... which explanation is correct ? ackleyman's or Beluebow's ?

As a general rule of thumb... I'll stand by my post...Ackleyman is full of good knowledge that he shares freely and often. IMO this was nothing more than a "typo" if you will.

The "real truth".....changing either powder charge or seating depth will change the size and shape of a group regardless of the initial shape.
 
I had forgotten about this thread. I know years ago a gun writer told me you go one way on horizontal groups and the other way on vertical groups with bullet seating depth. I found the PM on the subject I was thinking about.

What I was told was this from a gun writer and BR shooter: "With two touching and one out seat deeper" "Triangular group seat out longer." He recommended 1/4 turn on the seating stem at a time.
 
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It is all nice, and fun to think about!

I have had multiple occasions, and targets to prove it, during load development where adding powder to a horizontal group made the groups smaller.

Anybody who does load development will see their POI shift, and their groups get bigger and smaller along the way by a simple review of the target.
 
Beluebow's explanation is correct!!! I was backwards.

Vertical means add more powder or use a hotter primer, UNLESS you are shooting in a head wind.

Horizontal means change seating depth.

two bullets in a group and one out could be a whole lot of things, but I usually just continue load development. If the load development continues, then I just change powders.
 
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