Load Development Question

[Mikemci]

When working on load development, which do you do first and why do you think it is superior to the other?
1) Find your most accurate powder weight.
2) Find the best seating depth.

Thanks, Mike

 

[TheOtherZilla]

Personally I look at powder first.. Then when I get things as accurate as I can and decide on a load I start tweaking further to see if there is an improvement

 

[BoydAllen]

Generally, I start with light marks on the bullet and look for a charge. After I have one, I play with seating depth.

 

[PatMiles]

Generally, I start with light marks on the bullet and look for a charge. After I have one, I play with seating depth.

Light marks as in touching the lands?

 

[savagedasher]

First thin I do after the case is fire forum
I do a careful case prep trim uniform the primer pockets . Then I carefully check the internal case volume . Some I mark the with 1 for lite middle no marks heavy with two . X on the ones that. Are out of range .
I have found that Tenth of a grain change in the case I get the same SD . Or they basically print the same on paper tunner setting is close on all three . Larry

 

[Toby Bradshaw]

When working on load development, which do you do first and why do you think it is superior to the other?
1) Find your most accurate powder weight.
2) Find the best seating depth.

Both at the same time, as described in Tony Boyer's book.

Here's an example with my 30BR -- three powder charges (33.5-34.7gr H4198) and 4 seating depths (Wilson stem measurements, so longer is farther from jam). 3-shot groups @ 100yd.

 

[BoydAllen]

Light marks as in touching the lands?

Yes, a little farther in than touching, so that the marks are about a third as long as wide. To better see marks, I press a wad of 0000 steel wool around the bullet of a loaded round, and then turn the round while holding pressure on the bullet. This makes very fine scorings around the bullet, that do not hurt a thing and which make rifling marks much easier to see.

 

[Intheshop]

Bullet fit first here.

 

[PatMiles]

Both at the same time, as described in Tony Boyer's book.

Here's an example with my 30BR -- three powder charges (33.5-34.7gr H4198) and 4 seating depths (Wilson stem measurements, so longer is farther from jam). 3-shot groups @ 100yd.

View attachment 1020927

What's up with the flyers on the left side?

Sorry, I just had to do it.

 

[Mikemci]

Toby, all of those groups are quite good!
It seems like your rifle favors the 1.747 depth and combination of that and 34.7 gr. is deadly.

 

[headhunter1111]

I like to sort out seating depth at a conservative powder charge. Of course It also depends on the bullet. VLDs I find to be much pickier about seating depth. A hot load .015 jump might be too hot at .015 jam. Straightening out your seating depth first lets you find your best velocity/accuracy window. I also found this method for determining best velocity/accuracy/consistency http://www.6mmbr.com/laddertest.html
I will be trying this method next time around.

 

[GSPV]

I start with a basic seating depth for a given cartridge/bullet. Say 12 thou jam for a boat tail in a 6 BR.

Then, I shoot three shot groups along targets on a horizontal axis varying powder charge in 0.2 or 0.3 grain increments. Using the center of the groups, I'm looking for a range of powder charges in which increasing powder charge yields lower POI on the graph. I shoot it two or three times to verify the results. I want to do this at a relatively constant temperature.

I then park the powder charge in the middle of the graph and play with the seating depth to bring the group in.

I'm also looking at ES and SD on the velocity. If it's low, great. If it's not, I'll look for a different powder that fills the case better. Maybe try at a higher velocity node window, if the pressure will allow. Depending, I might also try more neck tension to see if it helps.

Once I have something that works, I already know how velocity changes as a function of powder charge with temperature constant. I'll then plot how velocity changes as a function of temperature with powder charge held constant.

Using these two graphs, I tune for constant velocity and can keep the vertical out.

YMMV