Judging ladder results

[Aaron47pb]

A 308 shooting 178 Amax with Varget from 43g to 45g in 0.2 increments at 400 yards:

So... what nodes do you guys see? And how much weight do you give 2 shot nodes?

Thanks

 

[Guest]

1 and 9 look good an so does 4 and 8

 

[Guest]

Interested in what charges those are?

 

[Aaron47pb]

Sorry, the charges corresponding to the shots are:

1 43.0gr
2 43.2gr
3 43.4gr
4 43.6gr
5 43.8gr
6 44.0gr
7 44.2gr
8 44.4gr
9 44.6gr
10 44.8gr
11 45.0gr

So I was thinking:

5-7 (43.8-44.2gr)
8-9 (44.4-44.6gr)
and ignoring the horizontal variance 10-11 (44.8-45.0gr)

But this is the first ladder test I've ever done and don't really know if trusting a 2 shot node is worthwhile.

 

[Darkside-Six]

You're pretty close with 5-7 and 8-9. I would load up 5 rounds of each load 5-9 and shoot some 5 shot groups to see which works best. That should narrow down a good load for you.


Sent from my iPhone using Tapatalk

 

[79jeepcj5]

I like 10-11. I usually go with .3 gr increments to get a little more vertical dispersion. To me it makes the nodes easier to determine.

Matt

 

[4Quangs]

The jumps between 7->8 & 9->10 & 2->3 tell me that those charges are not stable; Charges 3, 4, 5, 6 seem the most stable of the bunch.

The problem with ladder tests is separating shooter error from charge sensitivity. I prefer to watch the center to center elevation changes of 3 shot groups.

 

[Guest]

44.3g varget with 175smk is the high node for me. Others have reported a node around 44.3 as well.

 

[LR338nut]

If you could shoot that a bit further it would be easier to tell. I try to do my 0.2gr ladders at 600yds.

 

[Aaron47pb]

Thanks all. I figure I might as well just load a bunch of 5 round batches and shoot. I'll probably go from 43.8g to 45.0g in 0.1g increments.

For load development, are longer distances always better? If not, what distance do you suggest I shoot my groups at?

Thanks

 

[LR338nut]

Its not that longer distances are better. Its the small increments you are going up in powder. At 400yds it wont show much of a "ladder" because the muzzle velocity from your min to your max load isn't changing much. Which results in a tight, hard to read, group. By extending the distance you will extend the ladder and it will be easier to see where your barrel node is.

 

[Barrel Nut]

The jumps between 7->8 & 9->10 & 2->3 tell me that those charges are not stable; Charges 3, 4, 5, 6 seem the most stable of the bunch.<br />
<br />
The problem with ladder tests is separating shooter error from charge sensitivity. I prefer to watch the center to center elevation changes of 3 shot groups.<br/>

I agree with this #4 was just a shooter error....3,4,5,6 is a good node

 

[Deleted member 10043]

However carefully we handload our ammo, we have no way to load cartridges that will give us absolutely uniform performance from one round to the next, in either velocities or pressures. And if our cartridges happened to be perfectly uniform, our very finest (but not perfect) recording instruments would record them as slightly different. When we fire test lots, we'd like to know whether one test lot is more nearly uniform than another. But with all these variations, how can we tell?

-- Ken Howell

I give no weight for two shot nodes. However, this is interesting. He shot less than 1 MOA at 400 yards with a MV variance of about 100 fps. So this is useful information. He can calculate a least squares methodology with a=grains and b=distance from center of group and accomplish the same thing as shooting 5 shot groups for each step up. Since he shot an odd number (11) he can accomplish this for several grain loads. He can also do the same thing for MV. It is not that much math...

charge (grains)	velocity (ft/sec)	first difference (ft/sec)	second difference (ft/sec)	third difference (ft/sec)	fourth difference (ft/sec)
50	2,415
		+111
52	2,526		+12
		+123		-17
54	2,649		-5		-26
		+118		-43
56	2,767		-48
		+70
58	2,837

<tbody>
</tbody>

However, I suspect this will serve to show that two shot observations really have no basis that I am aware of but I'm willing to stand corrected.

 

[Barrel Nut]

I give no weight for two shot nodes. However, this is interesting. He shot less than 1 MOA at 400 yards with a MV variance of about 100 fps. So this is useful information. He can calculate a least squares methodology with a=grains and b=distance from center of group and accomplish the same thing as shooting 5 shot groups for each step up. Since he shot an odd number (11) he can accomplish this for several grain loads. He can also do the same thing for MV. It is not that much math...

charge (grains)	velocity (ft/sec)	first difference (ft/sec)	second difference (ft/sec)	third difference (ft/sec)	fourth difference (ft/sec)
50	2,415
		+111
52	2,526		+12
		+123		-17
54	2,649		-5		-26
		+118		-43
56	2,767		-48
		+70
58	2,837

<tbody>
</tbody>

However, I suspect this will serve to show that two shot observations really have no basis that I am aware of but I'm willing to stand corrected.

Ub.....huh?

 

[Deleted member 10043]

Uniform probability part of least squares. I stole it from somebody else who stole it from somebody else.

 

[steve123]

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