Seating depth or charge weight, first?

[Texas10]

One school of thought is both powder charge and seating depth affect barrel time. Powder is a coarse adjustment while seating depth is the fine adjustment so that ultimately the bullet exits the muzzle when the shockwave impulse is nearest the chamber.

Typically I start by seating off or in, depending upon the bullet design. Work the charge first, then the seating depth. However, since I only shoot for personal satisfaction and don't compete, I may be full of sh**.

YMMV.

 

[bsekf]

I use the Berger method, 1/3 turn on the seating stem between 3 shot tests. Using a middle powder charge. Pick out the best group and then do a 3 shot charge test using the best seating depth or depths.

Load 5 rounds of the best group, go to range to test ........and shoot patterns.

Go back home and start all over!

Berger says one of the seating depths will show a much better group. That has not usually been my experience. However, their method makes sense ...... to me. I seem to end up with 2 out of 5 tests looking good and they often are not in sequence.

Another note, I am using a 50 power scope at 200 yards, I dry fire after I have the gun set up. If the cross hairs jump 1/4 to 1/2 inch, the bullets can't go in the same hole!

Bill

 

[dcali]

In my experience it doesn’t really matter. If you really want to nail the best load you’ve got to do both. That is, if you want to test 4 charges and 4 seating depths, you need 16 groups. You can’t short cut by picking doing them separately because they’re not truly independent.

That said, the two factors are usually close to independent of each other, so if you’re not concerned about missing the last bit of optimization, you can do either one first.

I prefer to start with a ladder test to narrow down charge weight and then test seating depth in that area (and slight changes in charge weight if appropriate).