FPS Node

[SconnieRaised]

So they way that I learned to do my load development from an old wise man was to.

1 - Choose a bullet
2 - Choose a powder from published loads
3 - choose other components
4 - Load ladder @ 0.5 gr increments.
5 - Look for CONSISTENT fps gains in loads
6 - When 2 Loads flatten out next to each
other it’s a possibility you have a node.
7 - When such “node” appears, load in 0.2 gr
Increments between these 2 loads.
8 - After confirming “node” load 5 at charge
Weight and solidify “node”
9 - Load 10 and group.

This has worked flawlessly for me in the past but I had never ran into a lower fps at a higher charge like I did this time. That’s why I was thinking my rifle didn’t like this powder.

I’m going to sit down this evening and continue my ladder. Hopefully will go shoot it this weekend.


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If you're confident with a method that focuses velocity, I'd still recommend shooting 3 rounds (or at least 2) at each powder charge. With one shot at each 0.5 grain interval you're going to be wasting time and powder in chasing possible nodes that appear solely from random variability in the velocity of a given powder charge. You'll also probably be missing real nodes for the same reason. Taking the average velocity of the multiple shots at each charge is going to reduce the effect of random variability tremendously and provide much clearer data on the true behavior of a given charge. It'll also give you insight into the velocity spread for each powder charge. If you see two adjacent powder charges that generate similar average velocities and both have low velocity spread, then you're probably on to something.

 

[Harvey_NW]

I run a Lee neck sizing die for this rifle and have the neck tension set right at 2 thou. Does neck tension really affect velo that much anyway? Even if you are running a unmodified FL die from what I’ve seen you still don’t get more that 4-5 thou neck tension. I may be completely wrong here.

You'd be surprised how much standard dies squeeze necks down, and how much that contributes to springback, if you actually start measuring. But consistent neck tension will contribute to lower SD/ES.

You'll notice that good components and proper brass prep will typically result in a linear increase of velocity to powder charge, and that's why the guys that shoot for statistically valid data will say there's no such thing as a node. If you repeat a ladder enough times, the "flat spots" get lost in the noise. And despite math and ballistics, velocity doesn't always translate into vertical downrange. I just read about a benchrest guy that won with an ES of 40, or something like that.

 

[Wizbang]

You'd be surprised how much standard dies squeeze necks down, and how much that contributes to springback, if you actually start measuring. But consistent neck tension will contribute to lower SD/ES.

You'll notice that good components and proper brass prep will typically result in a linear increase of velocity to powder charge, and that's why the guys that shoot for statistically valid data will say there's no such thing as a node. If you repeat a ladder enough times, the "flat spots" get lost in the noise. And despite math and ballistics, velocity doesn't always translate into vertical downrange. I just read about a benchrest guy that won with an ES of 40, or something like that.

I have recently realized how much brass prep actually effects accuracy and speed, just didn’t know that your ES could be thrown off by a thou or so neck tension. Either way I now always check my neck tension with every round.


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[Wizbang]

If you're confident with a method that focuses velocity, I'd still recommend shooting 3 rounds (or at least 2) at each powder charge. With one shot at each 0.5 grain interval you're going to be wasting time and powder in chasing possible nodes that appear solely from random variability in the velocity of a given powder charge. You'll also probably be missing real nodes for the same reason. Taking the average velocity of the multiple shots at each charge is going to reduce the effect of random variability tremendously and provide much clearer data on the true behavior of a given charge. It'll also give you insight into the velocity spread for each powder charge. If you see two adjacent powder charges that generate similar average velocities and both have low velocity spread, then you're probably on to something.

So I loaded and continued my ladder prior to seeing your reply.

One shot at each charge

64.0 gr - 2705fps
64.2 gr - 2702fps
64.5 gr - 2674fps
64.7 gr - 2700fps
65.0 gr - 2717fps
No Pressure on any

Shot at 100 yds with magnetospeed put all 5 in 1/4 min group.

I still believe my previous load is better with H4350

60.5 gr @ 2753 with an ES of 15fps and shoots 1/4 MOA. I also have tons of data on this one with prob around 40 Rnds thought the chronograph and around the same grouped on paper.

Starting to think I’m stupid for trying something different.


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[TxLite]

5 RND’s
#1 - 61.5 gr @ 2665fps
#2 - 62.0 gr @ 2574fps
#3 - 62.5 gr @ 2714fps
#4 - 63.0 gr @ 2719fps
#5 - 63.5 gr @ 2756fps

64.0 gr - 2705fps
64.2 gr - 2702fps
64.5 gr - 2674fps
64.7 gr - 2700fps
65.0 gr - 2717fps

Is round 2 with the same powder as round 1?

 

[Wizbang]

Is round 2 with the same powder as round 1?

All same component’s and lot numbers.


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[TxLite]

All same component’s and lot numbers.

Same ambient temps and everything? No weird changes?

 

[Wizbang]

Same ambient temps and everything? No weird changes?

Only change was humidity. 80 % with the first round and 66% with the second.


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[ResearchinStuff]

What chronograph do you have?

 

[Wildstreak]

For a test to be statistically significant, it requires at least 30 data points.

 

[TxLite]

Only change was humidity. 80 % with the first round and 66% with the second.

It sounds to me like maybe there is some room for improvement in loading techniques or possible chrono error. I had similar consistency issues with my Caldwell chrono but have not had any issues with the magnetospeed. I would not expect for an additional 2.5gr of powder to produce the same velocity like you experienced with 62.5 and 65gr. Not to mention the 140 fps jump between 62 and 62.5. At a minimum I would rerun the test with one of the suggestions above with 3 shots per charge and see how the velocities fall.

 

[Wizbang]

What chronograph do you have?

Magnetospeed sporter


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[ResearchinStuff]

Hmm, I figured you were using an optical chrono with those results. Not really sure what to recommend.

Same number of firings on each case?

 

[Wizbang]

It sounds to me like maybe there is some room for improvement in loading techniques or possible chrono error. I had similar consistency issues with my Caldwell chrono but have not had any issues with the magnetospeed. I would not expect for an additional 2.5gr of powder to produce the same velocity like you experienced with 62.5 and 65gr. Not to mention the 140 fps jump between 62 and 62.5. At a minimum I would rerun the test with one of the suggestions above with 3 shots per charge and see how the velocities fall.

Well I’m pretty sure my chrono is working good. Both times I shot I also put a few across it from my load that I already developed. Same FPS as it always was.

Probably just my shity load techniques.


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[Wizbang]

Hmm, I figured you were using an optical chrono with those results. Not really sure what to recommend.

Same number of firings on each case?

Yeah, all have been once fired Nosler Brass.


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[ResearchinStuff]

Yeah, all have been once fired Nosler Brass.


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How consistent are their weights? Primer pockets all uniform? Flash holes all deburred?

Is your scale calibrated?

Something is jacked up, just can't tell what.

 

[ResearchinStuff]

Wait- one sized belted mag. Measure a bunch (ideally all) base to shoulder datum with a comparator and see how consistent your shoulder bump is on your sized cases. Inconsistent case volume could create what you're seeing, and a belted mag can take a couple firings to actually grow long enough to headspace off the shoulder.

Also measure your now twice fitted cases the same way, and compare to any unsized, one fired cases you still have. If the twice fired are longer than your one fired unsized, then your one fired were not fully fireformed, and you may need to further adjust your sizing die

 

[Mack84]

I think the satterlee guy would disagree with you. I use it, but I’ve not had the results with it that he gets. What it does do for me is gets me in the ballpark without burning a bunch of components.

I also agree, he’s got a ways to go before he has much issue.

My experience with Saterlee Method has been vast. Tried and tried and tried but rarely proved. So here’s where it improved. A larger sample size. Went to 2 shots at each powder charge to prove it side by side. My 6ARC accomplished a pronounced node that proved. Charge weights were .01 at 2 shots a piece which this case was only 24 bullets, primers, charge weights, etc.

With the 7 mag you could start at 61.6 and work up to 63.4 @ 2 tenths w/2 shots per charge weight.

61.6 - 2 samples
61.8 - 2 samples
62.0 - 2 samples
62.2 - 2 samples
Ect

 

[Harvey_NW]

My experience with Saterlee Method has been vast. Tried and tried and tried but rarely proved. So here’s where it improved. A larger sample size. Went to 2 shots at each powder charge to prove it side by side. My 6ARC accomplished a pronounced node that proved. Charge weights were .01 at 2 shots a piece which this case was only 24 bullets, primers, charge weights, etc.

Bump that sample size up to 20 or 30 and I bet that identifiable node disappears.

 

[Mack84]

Bump that sample size up to 20 or 30 and I bet that identifiable node disappears.

Ok. Are you telling me there’s no way to achieve consistency?