FPS Node

[Wizbang]

So I have a pet load for my 7mm but can’t help but tinker a little. Since I have 5lbs of H4831sc I thought I would try and build a new load using 168gr VLDH’s.

7MM REM MAG
Tikka action
20” barrel
1:8 twist
CCI 250
168gr VLDH
Nosler Brass
H4831sc

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
No pressure signs in any loads

It looks like I have a node between 62.5 & 63.0 gr but I’m not happy with the velocity. I get about 100fps more out of my already existing load. Could I find another node at a higher charge? Does the data (#1 & #2) point to my rifle not liking this powder?

My current load is 60.5 gr H4350 @ 2856fps with the rest of the components being the same.


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[Pickettpuncher]

Quit using half grain increments and go to .3 increments and those nodes are much more pronounced.

 

[Wizbang]

Quit using half grain increments and go to .3 increments and those nodes are much more pronounced.

Alright, I understand that but looking at this data with a starting load it of 61.5 gr and a velo of 2665 fps then a load of 62.0 gr with a lower velo of 2574 fps would that be an indication that my rifle doesn’t like this powder? Could I keep working up in my ladder from where I sit right now?


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[Pickettpuncher]

Alright, I understand that but looking at this data with a starting load it of 61.5 gr and a velo of 2665 fps then a load of 62.0 gr with a lower velo of 2574 fps would that be an indication that my rifle doesn’t like this powder? Could I keep working up in my ladder from where I sit right now?


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What I’ve found is that it’s not an indication of anything. Just hit a slow spot that I can’t explain, but I’ve seen the same thing that you have. .3 grains gives a better idea of how big the node is. Generally you look for 3 charges in a row that are close to the same. I had a 300 wm and I had 3 different charges within 5 fps. Load shot great too. The bigger the node the more forgiving it is. I do think you can continue loading hotter, but you need to watch for cratered primers and also a sticky bolt lift. You might start just under where your possible node is and work up in .3s until you find pressure signs or get way faster than you should be. I would think you should be around 3k fps with a 168 but barrel length may be hurting you some.

 

[Wizbang]

What I’ve found is that it’s not an indication of anything. Just hit a slow spot that I can’t explain, but I’ve seen the same thing that you have. .3 grains gives a better idea of how big the node is. Generally you look for 3 charges in a row that are close to the same. I had a 300 wm and I had 3 different charges within 5 fps. Load shot great too. The bigger the node the more forgiving it is. I do think you can continue loading hotter, but you need to watch for cratered primers and also a sticky bolt lift. You might start just under where your possible node is and work up in .3s until you find pressure signs or get way faster than you should be. I would think you should be around 3k fps with a 168 but barrel length may be hurting you some.

Alright. I appreciate the input. I was planning on continuing but getting another point of view on the subject always makes me feel a little better. I was hoping to get to around 2900 fps with a good node and grouping.


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[Pickettpuncher]

Alright. I appreciate the input. I was planning on continuing but getting another point of view on the subject always makes me feel a little better. I was hoping to get to around 2900 fps with a good node and grouping.


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Nosler data stops at 65gr. So I’d say you have a ways to experiment

 

[Harvey_NW]

Nodes don't exist, load to pressure and see if you can achieve the velocity you're happy with. If not, switch powders.

Edited to add - make sure your neck tension is consistent.

 

[ResearchinStuff]

*probably* don't exist.

If you really want to tinker, and contribute to rokslide science, load up the same ladder 10-30 times and see whether the nodes are real, or whether the velocity generally has a linear slope with powder charge.

 

[wind gypsy]

So I have a pet load for my 7mm but can’t help but tinker a little. Since I have 5lbs of H4831sc I thought I would try and build a new load using 168gr VLDH’s.

7MM REM MAG
Tikka action
20” barrel
1:8 twist
CCI 250
168gr VLDH
Nosler Brass
H4831sc

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
No pressure signs in any loads

Is that one shot at each charge? I find it hard to believe you'd lose 90 FPS with 0.5 grain larger charge. If you're only shooting one charge each, this is a fantastic illustration of why trying to find a "node" with this method is worthless.

You can definitely go higher.

 

[Wizbang]

Nodes don't exist, load to pressure and see if you can achieve the velocity you're happy with. If not, switch powders.

Edited to add - make sure your neck tension is consistent.

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.


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[Wizbang]

*probably* don't exist.

If you really want to tinker, and contribute to rokslide science, load up the same ladder 10-30 times and see whether the nodes are real, or whether the velocity generally has a linear slope with powder charge.

That would be really cool but with the amount of money and components I have (or lack) it’s kinda unfeasible for me. Part of the reason I’m even doing this load development is to use powder that I already have as in starting to run low on h4350. I know that there has been more of that available as of late but I’m a “eat what’s on your plate before you ask for 2nds” kind of guy.


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[Wizbang]

Is that one shot at each charge? I find it hard to believe you'd lose 90 FPS with 0.5 grain larger charge. If you're only shooting one charge each, this is a fantastic illustration of why trying to find a "node" with this method is worthless.

You can definitely go higher.

Yes, just one shot per charge. What method do you use to find a good load? I appreciate all input as I have only been reloading my own rounds for about 4-5 yrs.


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[Pickettpuncher]

this is a fantastic illustration of why trying to find a "node" with this method is worthless.

You can definitely go higher.

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.

 

[wind gypsy]

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.

His results are a perfect example of why the satterlee method doesn't "find a node". No way if a guy loads up 10 rounds at 61.5 and 10 @ 62.0, is the avg going to be faster @ 61.5. Yet here we are, looking at data showing 62.0 being 90 FPS SLOWER than 61.5 and considering "where the node is" in the data? Taking single shots with ammo that appears likely to have about a 100 FPS ES and thinking a repeatable velocity node is being shown isn't reasonable.

 

[Pickettpuncher]

His results are a perfect example of why the satterlee method doesn't "find a node". No way if a guy loads up 10 rounds at 61.5 and 10 @ 62.0, is the avg going to be faster @ 61.5. Yet here we are, looking at data showing 62.0 being 90 FPS SLOWER than 61.5 and considering "where the node is" in the data? Taking single shots with ammo that appears likely to have about a 100 FPS ES and thinking a repeatable velocity node is being shown isn't reasonable.

I don’t disagree with your assessment. A higher charge should be faster. But I also think it shows that the charge isn’t optimal and you continue on. I don’t understand why the velocity may drop but I’ve seen it multiple times. An average of 5 shots may prove better but you’re burning a bunch of components getting there. Personally, I use the method to get my baselines. And what I settle on velocity wise is in conjunction with my initial testing.

 

[ResearchinStuff]

That would be really cool but with the amount of money and components I have (or lack) it’s kinda unfeasible for me. Part of the reason I’m even doing this load development is to use powder that I already have as in starting to run low on h4350. I know that there has been more of that available as of late but I’m a “eat what’s on your plate before you ask for 2nds” kind of guy.


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Then your best bet is to use the form method already linked.

 

[Pickettpuncher]

*probably* don't exist.

If you really want to tinker, and contribute to rokslide science, load up the same ladder 10-30 times and see whether the nodes are real, or whether the velocity generally has a linear slope with powder charge.

You send me the supplies and I’ll do the test. I have a chronograph. 280ai or 25-06. Take your pick.

 

[SconnieRaised]

Yes, just one shot per charge. What method do you use to find a good load? I appreciate all input as I have only been reloading my own rounds for about 4-5 yrs.


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I wouldn't rely solely on velocity. Understanding velocity is helpful but at the end of the day, it's the loads that hit together on paper that are the ones you'll want to target. Sometimes they also group by velocity, sometimes not.

My method is finding the max load and then taking one shot with 0.2 grn increments over the range from max down to 4 or 5 grains less. Then I dig into several of the windows with promise with another 10 to 15 loads to confirm the node and find the sweet spot.

In general, the more shots you put into the ladder, the more certainty you'll have on where anode is and less impact there will be if you pull a shot. But a single shot every 0.5 grain isn't going to get you there with confidence.

 

[Wizbang]

I wouldn't rely solely on velocity. Understanding velocity is helpful but at the end of the day, it's the loads that hit together on paper that are the ones you'll want to target. Sometimes they also group by velocity, sometimes not.

My method is finding the max load and then taking one shot with 0.2 grn increments over the range from max down to 4 or 5 grains less. Then I dig into several of the windows with promise with another 10 to 15 loads to confirm the node and find the sweet spot.

In general, the more shots you put into the ladder, the more certainty you'll have on where anode is and less impact there will be if you pull a shot. But a single shot every 0.5 grain isn't going to get you there with confidence.

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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[TxLite]

For reference I ran my 22” 7mm-08 to 2720 with an SD of 8.3 with the 168 vldh @ sub 3/4 minute. You should have a lot more room to go in your 7 mag.