Very strange ladder tests

[six pack]

Working up loads for my grandsons Kimber 84M in 7-08. Once fired Lapua brass FL sized and bumped .002. CCI BR2 primers. 140g Nosler Partitions seated .03 off. H4350 powder weighed on a Gem scale. Looking for nodes and can't make heads or tails out of the results. Candidly, I'm not sure I see any nodes at all. Ammo assembled at the same sitting. Ran two tests for confirmation. Anybody experienced this before?

Load. A. B

45.6. 2809 2803
45.8 2820 2826
46.0 2842 2817
46.2 2853 2818
46.4 2856 2838
46.6 2897 2839
46.8 2892 2827
47.0 2879 2913
47.2 2894 2945
47.4 2920 2917
47.6 2894 2887

 

[cohunt]

what chronograph?

 

[six pack]

MagnetoSpeed V3

 

[palerider3]

45.8-46.8 looks like a huge node to me. I'd load 10 at 46.3 and shoot them. See what your SD and ES are. I bet you're good. That said the reason for the variation at the top could be symptom of inconsistent bullet base to ogive. I doubt it'll be much of a problem at the distances he'll be shooting a partition.

 

[cohunt]

pressure signs? and this is H4350 and not IMR 4350 right?

 

[tdot]

I've used exactly one Gem scale, but it was inconsistent. Apparently that's not uncommon. You may have different powder charges.

 

[fiftybmg]

45.6 , 47.4 and 47.6 show promise.

How do you define a node ?

My understanding of a ladder test is to load 5 rounds per charge, and shoot one round per charge per target, till all 5 are shot.

Charge 1 round 1 target 1,
charge 2 round 1 target 2,
charge 3 round 1 target 3 etc,

then cycle back to charge 1 round 2 target 1, and so on.

Then measure group size.

I find that the rounds with the least deviation provide best group size, in my rifles, ie : 0.5 MOA at 100 meters which carries true to 300 meters.. I understand barrel harmonics is a thing, but I can't shoot well enough to find it.

 

[six pack]

pressure signs? and this is H4350 and not IMR 4350 right?

None noticed. Yes, H4350

 

[six pack]

I've used exactly one Gem scale, but it was inconsistent. Apparently that's not uncommon. You may have different powder charges.

I guess anythings possible but I haven't noticed it before. Seems to be OK with other rifles. I've owned it about 5 years.

 

[Mram10us]

I'd be lost too. Sorry. I agree with the post above regarding different charge weights. Not often you see a 50fps spread

 

[cohunt]

Id try around 46.4 again-- but that "set B" looks very erratic --- either something wrong with chrony or powder charge is my guess

did you record the shots on the target? or just shoot them for speed?
did you shoot all "set A" first then "set B"? how long did you wait between each shot?
outside temp?

 

[tdot]

If it wasn't for the Gem Pro use, the other thing I would have suggested is that it looks like there might be the top end of a node at 45.6/45.8.

I've only played with a 7-08 briefly a few years ago, but I recall 46 grains and 2800fps to be close to max. Where did you get your data from?

I've found inconsistent ladder test results while approaching max pressure.

 

[cohunt]

If it wasn't for the Gem Pro use, the other thing I would have suggested is that it looks like there might be the top end of a node at 45.6/45.8.

I've only played with a 7-08 briefly a few years ago, but I recall 46 grains and 2800fps to be close to max. Where did you get your data from?

I've found inconsistent ladder test results while approaching max pressure.

hodgdon web page shows 48 as mx iirc, different 140 gr bullet though-- and they do show 2868 as max speed for H4350 so he could be overr pressur with the partitian bullet

46 is around max for the IMR, thats why I asked him earlier about IMR vs H

 

[six pack]

Id try around 46.4 again-- but that "set B" looks very erratic --- either something wrong with chrony or powder charge is my guess

did you record the shots on the target? or just shoot them for speed?
did you shoot all "set A" first then "set B"? how long did you wait between each shot?
outside temp?

Shot for speed. Fired load from A then same load from B. Temp about 78-80.