Load development - ladder test - what does this tell me?

[CSGambill]

I was tried to do a ladder test today for my .338 Lapua. 600 yds. Used Hodgdon 1000, from 88.0 to 89.5gr in 0.3 increments. 300gr Lapua Scenar bullets. Wind was gusting to about 10 mph. Got the following results. I'm not sure what to make of it. I expected more vertical deviation and less overlap. Do I need to go out farther than 600? Shooter error? Thoughts?

 

[502Chevelle]

You need to run it farther out so you have more vertical dispersion. Also color your bullets per load with a sharpie. When they go through white paper, they will leave a color ring and you can see which bullets belong to which groups. For example, color the 88s red, the 88.3s green, the 88.6s black etc. when you go check out your target, you will have all the pretty colored rings to compare. If you shoot from more distance, and have more vertical dispersion between groups, you will see how far apart the groups are, but several groups will be tighter vertically. This is your accuracy node with that powder, and then you can refine the load more in that area. I hope all this makes sense. It's a lot easier if you actually see it done.

 

[502Chevelle]

Just went and looked at a good article. Didn't know if I'd be able to find it, check out 6mmbr.com , enter "ladder" in the search block, and the first article that came up is a very good one on how to do this test.

 

[dauntedfuture]

.3g is not enough of an increment for a .338 to show things well. .5g in a .308 is 1%, or about 1g in a 89g capacity case. try 1g increments and see what happens. With that said, it looks like there is more of a group with 1-2-3 and the 5's are high. Chronograph your loads at the same time, you should see high shots are higher velocity but this is not always that case. Pay attention to vertical spread more then horizontal dispersion. With that said, triangulate each group and plot the center of each group, 1, 2, 3, 4, 5 6. I think you will find that the center of each 3 round group is close together.