(UPDATE) Which node would you use?

[Thump_rrr]

I replaced the barrel on my 6.5 Creedmoor over the winter and ran a new ladder test today.
Conditions weren’t ideal with an 18 mph wind with gusts up to 30mph.
Temperature was 32F

Lapua brass, CCI BR-4, H4350, 140gr ELD-M
I found 3 nodes at 39gr, 40.2gr and at 41.4gr.

At 39gr the average velocity was 2670 FPS, ES 9.51, SD 4.02. Drop at 600M is 4.3 MRAD.

At 40.2gr the average velocity was 2737 FPS, ES 11.49, SD 4.81 Drop at 600M is 3.9 MRAD.

At 41.4 the average velocity was 2830 FPS, ES 13.07, SD 5.57. Drop at 600M is 3.3 MRAD.

The most accurate node was the lowest at 0.35moa.
The next best was the middle node at 0.56moa.

I will be shooting a clinic out to 600m in 3 weeks.
Is there any disadvantage to shooting the lowest load?

 

[Dogtown]

Sometimes the mild load is the most consistent. We all like to chase velocity to a degree for the obvious advantages, but if your rifle likes that combo in a milder load then that’s what you should pay attention to.

If you have time do the test again and see if you get similar results, especially give the conditions you originally shot under.

 

[Precision Underground]

I’ll reply here as I didn’t realize we were in someone else’s thread over there. Do you have pictures of the entire test? That would be the only way for anyone to know if either charge is preferable. I look at tests with the thought that a .5 group and a .3 group are essentially the same. The amount of movement it takes at the muzzle to go from a .3 group to a .5 group is absurdly small. If you’re solely going off of a few groups, 9/10 times it’s very likely that the load was not the difference in .3 and .5.

That’s not me saying to chose the faster charge. Speed may be a consideration depending on what you’re doing but what really matters is what’s happening on either side of the good groups. You want a load that’s stable throughout variations in temp, powder charge, primer lots, etc…. Looking at the impacts next to the good groups is the only way to know where that charge is.

 

[Thump_rrr]

I’ll reply here as I didn’t realize we were in someone else’s thread over there. Do you have pictures of the entire test? That would be the only way for anyone to know if either charge is preferable. I look at tests with the thought that a .5 group and a .3 group are essentially the same. The amount of movement it takes at the muzzle to go from a .3 group to a .5 group is absurdly small. If you’re solely going off of a few groups, 9/10 times it’s very likely that the load was not the difference in .3 and .5.

That’s not me saying to chose the faster charge. Speed may be a consideration depending on what you’re doing but what really matters is what’s happening on either side of the good groups. You want a load that’s stable throughout variations in temp, powder charge, primer lots, etc…. Looking at the impacts next to the good groups is the only way to know where that charge is.

I’ll reply here as I didn’t realize we were in someone else’s thread over there. Do you have pictures of the entire test? That would be the only way for anyone to know if either charge is preferable. I look at tests with the thought that a .5 group and a .3 group are essentially the same. The amount of movement it takes at the muzzle to go from a .3 group to a .5 group is absurdly small. If you’re solely going off of a few groups, 9/10 times it’s very likely that the load was not the difference in .3 and .5.

That’s not me saying to chose the faster charge. Speed may be a consideration depending on what you’re doing but what really matters is what’s happening on either side of the good groups. You want a load that’s stable throughout variations in temp, powder charge, primer lots, etc…. Looking at the impacts next to the good groups is the only way to know where that charge is.

Here is the complete target.
photos upload free
The first row are foulers.
As mentioned above it was 32F with an 18mph wind and 30mph gusts.
I was seriously considering packing up after my foulers but I’m running out of time.
The second page literally blew away but there is nothing mind blowing on it.

This weekend is my last chance and they are calling for 52F and sunny on Easter Sunday.

I will load everything back up in .2gr increments and try again.

 

[Precision Underground]

Here is the complete target.
photos upload free
The first row are foulers.
As mentioned above it was 32F with an 18mph wind and 30mph gusts.
I was seriously considering packing up after my foulers but I’m running out of time.
The second page literally blew away but there is nothing mind blowing on it.

This weekend is my last chance and they are calling for 52F and sunny on Easter Sunday.

I will load everything back up in .2gr increments and try again.

Yea the missing data in between the .4 increments makes it hard to really read it with confidence but if you call 38.2 and 39.4 scatter nodes, the 1.5% lines up pretty well with the two better groups. The scatter node has always held pretty true in my tests. A 2750ish speed is usually where my loads shoot well and that’s plenty of speed to get out there so I’d be loading around that node in .2s. I think you’ll be fine there. That group would be just as good as the slower one if the one round wouldn’t have dropped a little low out of the group.

 

[Doom]

I'll add another thought. the 39 and 40.2 points of impact fall on the same point which is also typical of "nodes". I would test 38.8, 39, 39.2 and 40, 40.2, and 40.4. That should bracket your loads.

 

[Thump_rrr]

Yea the missing data in between the .4 increments makes it hard to really read it with confidence but if you call 38.2 and 39.4 scatter nodes, the 1.5% lines up pretty well with the two better groups. The scatter node has always held pretty true in my tests. A 2750ish speed is usually where my loads shoot well and that’s plenty of speed to get out there so I’d be loading around that node in .2s. I think you’ll be fine there. That group would be just as good as the slower one if the one round wouldn’t have dropped a little low out of the group.

The 39.0 came in at 2670 ave, 9.51 ES, 4.02 STD.
2665, 2672, 2672, 2675, 2666.

The 40.2 came in at 2737 ave, 11.49 ES, 4.81 STD.
2740, 2740, 2740, 2729, 2735.

 

[bax]

Here is the complete target.
photos upload free
The first row are foulers.
As mentioned above it was 32F with an 18mph wind and 30mph gusts.
I was seriously considering packing up after my foulers but I’m running out of time.
The second page literally blew away but there is nothing mind blowing on it.

This weekend is my last chance and they are calling for 52F and sunny on Easter Sunday.

I will load everything back up in .2gr increments and try again.

Another point of view ... look at 38.6 and 39.0. Remove the wind from 38.6 and you get 39.0. Vice versa, add wind to 39 and you get 38.6.

Maybe. Maybe that horizontal isn't wind. Maybe the barrel is moving at 38.6. More testing needed.

Where is bullet 5 in 39.4? I see four holes.

Are you testing at 100 yards?

I don't like the vertical in all of those targets. A node is (or, at least, should be) a small round spot or mostly round and spread a little horizontal. I think with 0.4 gr jumps you are missing the node.

In a perfect world, you get vertical one or more of these:

• either from the barrel still moving in the vertical plane - you are not in a node
• powder charge is not uniform - some bullets are faster than others, faster ones get to the target quicker so they don't drop as much and so they hit the target higher. I saw this two weeks ago. Fourteen shots, random mix 20 fps difference drew two horizontal lines on the target about 3 inches apart. A 10 fps difference printed right between the lines. It was an amazing demonstration.
• The wind - a cross wind creates lift on the bullet. Seems to me that a right-hand twist and a from-the-left crosswind makes the bullet drop. That might be exactly backward but there is a crosswind lift effect.

I never make gun handling errors so those are the only possible sources of vertical on my targets.

If you believe that, please ask about the bridge I have for sale.

Horizontal comes from not-in-a-node, wind, and gun handling. Since the exact effect from wind is unknowable, I don't mind seeing a little horizontal during load development - especially if I can look at wind flags (or veg, smoke, clouds, dust, etc) and explain the hit.

 

[Thump_rrr]

Another point of view ... look at 38.6 and 39.0. Remove the wind from 38.6 and you get 39.0. Vice versa, add wind to 39 and you get 38.6.

Maybe. Maybe that horizontal isn't wind. Maybe the barrel is moving at 38.6. More testing needed.

Where is bullet 5 in 39.4? I see four holes.

Are you testing at 100 yards?

I don't like the vertical in all of those targets. A node is (or, at least, should be) a small round spot or mostly round and spread a little horizontal. I think with 0.4 gr jumps you are missing the node.

In a perfect world, you get vertical one or more of these:

• either from the barrel still moving in the vertical plane - you are not in a node
• powder charge is not uniform - some bullets are faster than others, faster ones get to the target quicker so they don't drop as much and so they hit the target higher. I saw this two weeks ago. Fourteen shots, random mix 20 fps difference drew two horizontal lines on the target about 3 inches apart. A 10 fps difference printed right between the lines. It was an amazing demonstration.
• The wind - a cross wind creates lift on the bullet. Seems to me that a right-hand twist and a from-the-left crosswind makes the bullet drop. That might be exactly backward but there is a crosswind lift effect.

I never make gun handling errors so those are the only possible sources of vertical on my targets.

If you believe that, please ask about the bridge I have for sale.

Horizontal comes from not-in-a-node, wind, and gun handling. Since the exact effect from wind is unknowable, I don't mind seeing a little horizontal during load development - especially if I can look at wind flags (or veg, smoke, clouds, dust, etc) and explain the hit.

I have just finished reloading 3 rounds each 38.6, 38.8, 39.0, 39.2, 39.4 39.6, 39.8, 40.0, 40.2, 40.4, 40.6 in FC cases.
I'm not sure what I will do with the Lapua since I still have 55 rounds loaded at 41.3 and was running around 2825-2830 FPM.
The best day for the test would be Monday with temps in the high 50's.
Temps in the 40's this weekend.

As for the 5th round in the 39.4 target


Here is another one of my targets shot with my CZ457.
Each target has 5 shots in it.
Shot at 25m.

 

[Thump_rrr]

Update: I re-shot the ladder in 0.2gr increments from 38.6 to 40.6
Much better in calm conditions.
39.0 and 40.2 are still holding up.

Any suggestions?

 

[BuildingConceptsllc]

Update: I re-shot the ladder in 0.2gr increments from 38.6 to 40.6
Much better in calm conditions.
39.0 and 40.2 are still holding up.

Any suggestions?

40.2 should be good for you and the poi is the same across 40.0 - 40.4, as best as can be said from this one target. Thats what you are looking for. It's a better target than before but it still doesn't really show the poi move or stay in a specific place beyond what they all generally show. Do seating depth test with 40.2 , (assuming you are not having any pressure at all there), and you will be good to go.

You need to use one type of brass and let that be it for load development. Changing the brass changes your load so, whatever brass you will use is what you want to develope a load with. Then once you have it, you can find what charge that same speed is in the other brass and use that with the same seating depth.

 

[Doom]

I would stay with 39 gr unless you absolutely need the extra velocity. It will save the cases.

 

[psharon78]

The most accurate and consistent node is the one I'd go with. I went with the lowest node on my rifle.