Seating depth question

[garandman]

In trying to think thru which to do first, either : (1) finding a paticular powder charge for best accuracy vs. (2) finding a particular seating depth for best accuracy, I'm wondering....

Should I expect a particular seating depth to group just as well at every powder charge quantity?

Hhhhmmmm......

 

[Texas10]

Hopefully someone will post a link to a thread here on that very issue, and working up a load using three charge wts at each seat depth. That's three rounds per seat depth, a starting charge, mid, and max. The ideal seating depth will show good tolerance to charge wt changes.

 

[Terry]

A good seating depth will still be better than others at different powder charges.

 

[garandman]

Is there good reason to work on seaing depth BEFORE powder charge? I've heard different opinions....

 

[Tim Singleton]

Best to do it all at once on the same target easier to see what's going on

 

[Tim Singleton]

Oh and do it on the worst day possible dont hold your shots
One seating depth will stand up to the wind better than the rest

 

[powderbrake]

I suggest that starting with a seating depth, you find the best charge, then go back and find the best seating depth at that charge. Then you are only changing one thing with each test.
I suggest starting the seat depth at "just touching"

 

[CharlieNC]

In Tony Boyer's book he will load a full matrix along the line of 5 depths x 5 charges = 25 total combinations, using 2 each to assess the best combination in terms of group size [ every body knows that small sample size will not work, right?]. Unless there is only a unique combination, it is not necessary to load all 25 possible combinations. I typically load 5 depths and 5 charges with 2 each using a "statistically" designed scheme involving 9 loads vs 25. This type of approach is both more efficient in terms of requiring fewer loads, and will determine if the best seating depth depends on the particular charge weight. The results are clear based on evaluating changes in point of impact (eg ladder type of interpretation), but in terms of group sizes a shooter error or puff of wind can lead to uncertainty using only 2 per load. So a followup using more shots is usually in order to finalize / confirm the choice. And it helps to have stat software for the evaluation of the results.

 

[dsculley]

I used to go powder first then seating depth. I reversed that a few years ago and I don't chase my tail as much. Now I first do the Berger seating depth test no matter what bullet I am using. I find the best depth in this test then test around that depth to refine it. Once I have a good depth node I will test for powder. After I find the powder node I may test the depth node a bit more but usually don't change the seating depth. As another shooter puts it "Seating depth is a coarse adjustment and powder charge is a fine adjustment."

 

[newbieshooter]

Hopefully someone will post a link to a thread here on that very issue, and working up a load using three charge wts at each seat depth. That's three rounds per seat depth, a starting charge, mid, and max. The ideal seating depth will show good tolerance to charge wt changes.

http://forum.accurateshooter.com/th...-or-powder-charge-come-first-and-why.3969156/

http://forum.accurateshooter.com/threads/load-development-with-seating-depth-first.3977374/

http://forum.accurateshooter.com/threads/bullet-depth-vs-powder-charge-which-first.3957075/

 

[Doom]

I used to go powder first then seating depth. I reversed that a few years ago and I don't chase my tail as much. Now I first do the Berger seating depth test no matter what bullet I am using. I find the best depth in this test then test around that depth to refine it. Once I have a good depth node I will test for powder. After I find the powder node I may test the depth node a bit more but usually don't change the seating depth. As another shooter puts it "Seating depth is a coarse adjustment and powder charge is a fine adjustment."

Before all of the "new" bullets arrived I think powder was the answer since most of the bullet profiles were similar. With the myriad of bullets out there I think this may be way to go. I personally haven't used it because I have stayed with the SMK in 308. However, I am considering the ELD-M's so this may be the approach I take.