6.5 CM Ladder/OCW Test Advice

[Bmars06]

Greetings,

I'm looking for some expert eyes to give me their opinions on my ladder test I performed today for a new 6.5 CM load. Three pictures are attached of the targets, shot at 200 yards. There are three target papers, each with five small targets on them. The small targets are numbered 1-15 and have a three-shot group fired at each of them. Targets numbered 1-7 are with a Berger 140gr Match Hybrid Target projectile starting at 40.0 grains of powder and going up by .3 increments to 41.8 Targets numbered 8-15 are with a Hornady 140gr ELD-M projectile starting at 40.0 grains of powder and going up by .3 increments to 42.0. The powder charges and the overall spread of the group is written next to the individual target as well. I'm having a hard time discerning where the optimal charge weight (OCW) appears to be.... I appreciate any guidance/advice!

Here are the velocities of each projective/charge:

Berger 140gr Match Hybrid Target
40.0 Grains of powder
-2609
-2619
-2614

40.3 Grains
-2609
-2609
-2636

40.6 Grains
-2640
-2624
-2629

40.9 Grains
-2677
-2672
-2688

41.2 Grains
-2704
-2726
-2704

41.5 Grains
-2766
-2754
-2737

41.8 Grains
-2777
-2766
-2772

Hornady 140gr ELD-M
40.0 Grains of H4350
-2645
-2645
-2656

40.3 Grains
-2666
-2682
-2656

40.6 Grains
-2704
-2677
-2699

40.9 Grains41.2 Grains
-2732
-2801
-2743

41.5 Grains
-2766
-2760
-2777

41.8 Grains
-2777
-2772
-2777

42.0 Grains
-2801
-2789
-2789

[ShaunBrady]

Were the targets shot as the attachments present them, or rotated so the writing is up?

[broadside]

based on the images, you need to shoot more than 3 rounds per load, unless these are all fired from a well setup sled and it's not you as the shooter.

[smoothy8500]

I'm assuming the pictures got rotated when posted? Regardless, what aspect of the OCW test are you looking for: Group center closest to POA? Flattest vertical dispersion? Plateau of elevation change with increasing charges? Velocity node? Your "test" is mixing Newberry's OCW, Satterlee, etc.

If you know that the vertical dispersion is not influenced by you, there are some groups where elevation change with charge, and the vertical dispersion of the group itself is fairly flat: 3&4, 9&10, 13&14.

[ar15barrels]

Why do people call group testing "ladder testing"?

Shooting groups at varying charge levels does not create a ladder on the target.
It creates a bunch of groups.

Ladder testing is when you fire a sequence of single shots all at the same aiming point to create a "ladder" and then you look at the "rung" spacing to find the nodes.



Ladder testing is best done at 300yds or more to get better rung separation.
I did my ladders at 600yds with a spotter at the target so it was easy to mark the individual shots.

[smoothy8500]

Why do people call group testing "ladder testing"?

No kidding. There must be several of these quasi "laddergroup" questions per week here.

[Fjold]

Ladder testing is to see where different loads group closer together to locate particular "vibration nodes" of barrels where the barrel is more consistent. If you look at Randall's photo that barrel likes that particular bullet and powder combination near 30 grains.

You shoot one shot with a number of slightly larger amounts of powder at the same aiming point on the target and track where each individual bullet lands. The further the target is from you that you can shoot accurately, the better. Shooting a ladder correctly depends on your ability to hold an accurate aiming point at distance and you're ability to shoot consistently for every shot.

You need a second person behind the berm at the target, a remote camera or an electronic target to keep the bullet holes in order. You are looking for vertical position of each bullet more than the horizontal spread.

Where the barrel groups the slight differences in powder charges together tells you where to do the final load development. Sometimes you'll have two or more "nodes" where your barrel likes different powder levels/velocities.

[Bmars06]

Thank you guys for the info! This is definitely a fun learning experience!

[p1choco]

41.5-41.8 seems like you're close to a stable velocity node. I don't know what your brass prep is like and I don't know what you're doing for neck tension. Personally if pressure signs are good in that range of powder, I would ensure you're getting the best possible consistency in regards to neck tension. Then play with seating depth and see if you're groups tighten up. Just my 2 cents.

[SmokeTheClay]

Thank you guys for the info! This is definitely a fun learning experience!

Satterlee method is trash. Dont use it. 3 groups is in fact a good idea for a starting point. If this was virgin brass I'd retest it. Maybe make sure youre using a good rest.

Here is a good method to follow. Since you're using ELDs and Berger Hybrids, then you'll most likely need a bigger jump than .0200

https://forum.accurateshooter.com/threads/long-range-load-development-at-100-yards.3814361/

[p1choco]

Satterlee method is trash. Dont use it. 3 groups is in fact a good idea for a starting point. If this was virgin brass I'd retest it. Maybe make sure youre using a good rest.

Here is a good method to follow. Since you're using ELDs and Berger Hybrids, then you'll most likely need a bigger jump than .0200

https://forum.accurateshooter.com/th...yards.3814361/

Eww! Starting at Jam? What a horrible idea and a complete waste of components.

Edit: read Bergers manual or Glen Zedikers book. It's a source of good information if you're after precision. Also keep in mind magazine restrictions. Modern testing with "big" bullet jump is showing amazing results. I don't know what your information intake is but maybe it would be worth learning more before you start doing more.

[SmokeTheClay]

Eww! Starting at Jam? What a horrible idea and a complete waste of components.

Edit: read Bergers manual or Glen Zedikers book. It's a source of good information if you're after precision. Also keep in mind magazine restrictions. Modern testing with "big" bullet jump is showing amazing results. I don't know what your information intake is but maybe it would be worth learning more before you start doing more.

Lol. You just slammed Erik Cortina. He'd probably wipe the floor with you with both eyes closed.

This is from 2014, and more suited to VLDs not hybrids or ELDs that like jump which is why I mentioned a bigger jump than .0200

[p1choco]

Slammed? Hardly. It is older, albeit great info. I will admit, I may have jumped the gun on what discipline the op is shooting. For PRS I would be more inclined to use the Satterlee method. For F Class, Erik's method is what I pretty much used. My current experience and results drive my current loading process. The OP will find their way.