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6 Dasher H4350 Load Development?

HTSmith

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So I just started to try to develop a load with H4350 for my Dasher because I have more of that than Varget or R15. I shot the horizontal row with charges increasing 0.2 Gr from 33.6 Gr to 35.2 Gr w/ Berger 108's seated about .015" off the lands. I wished I'd loaded a 35.4 Gr. charge but I'm not sure I could have seated the bullet to length with that much powder. I felt good about all the shots and there was almost no wind. The aim points were the intersection of the grid lines closest to the respective hole. There were no pressure indications. I've heard about looking for speed flat spots and impact flat spots and I'm not sure where to go next. What would you do next and why? Thanks for taking time.
 
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I'm not sure that testing regime will tell you much. It's alluding to a long range ladder test but isn't at least 300yds. If that's what you're chasing, the three lighter loads with the exact same elevation look the most promising but I wouldn't read anything into that limited data/distance.
 
Individual shots. I was trying to find my max charge and figured I'd shoot them this way. I'm not sure I can get enough H4350 in the case to make pressure.
Tim, I realize that components are tight these days, but a single shot per step makes the interpretation of this method kinda risky.

What is your end goal?

For example do you want to run short range bench rest or are you looking to play mid range or long range?

1626402294739.png

This isn't much to go off of, but since you asked... this would say to investigate 33.7 and 34.3 to see if those are in fact repeatable "flat" spots with good speed stats, then go tune for seating depth. Wish there was more samples per step, but I understand not wanting to burn any more than you need to in order to tune a load these days.
 
RegionRat, first I can't thank you enough for taking time (and skill) to put this into a graph. Makes it very easy to see. Second my club only has a 100 yard range. I hope to try out to 600 yards, but I have very limited opportunity to practice and test at range. My primary goal with this test was to find my maximum charge of H4350. Turns out I ran out of case capacity before I hit pressure, but I now know my working range and, 2900 fps is plenty fast for me.

I'm going to try those speed flat spots on the chart for sure. Question, would you pay any attention to the points of impact of the various loads?

Thank you again.
 
@Stan Taylor nailed it...

The velocities on your chart are single samples and are important but cannot get us all the way to the goal.

Yes, your groups are just as important as your velocities when testing at short range and extrapolating to longer ranges.

Tuning a gun is done because it makes a very big difference. External ballistics and group performance at range are non-linear and that regression straight line on the plot is just one example of this. When you tune your rig, the recipe includes lots of parameters but let's make this a shorter talk and stick to the simplified version that says you are searching for the correct charge and depth.

The speed and charge relationship is basically linear but those waves are what we are searching for in terms of tuning. The impacts and groups are similar in that they don't respond to incremental changes in powder in a linear way. We are trying to find the advantages of being at the right speed, with a charge that gives the best groups, and if at all possible the best velocity stats in case we want to use that load at unknown distances.

A tight group at any distance is great, but they sometimes don't align to the best velocity stats. Make no mistake about it, when you see a great group at 100/200 with poor velocity stats, it generally falls apart at distance. The opposite is also true, when you see a tight group at 100/200 and it also has great velocity stats, it generally holds together at distance.

If you are trying for 600 yards, then play with the ballistics calculators and you will find that your velocity stats just need to be decent to keep the hypothetical vertical under control. In reality, there are many accomplished shooters that don't own a chrono and don't care about their velocity stats cause their groups are good. If you push a good 600 yard load to 1000 with a velocity stat that isn't state of the art, don't expect to play in the big leagues.

You can do fine with a decent velocity stat and short range testing to get out to 600. Your group testing will typically reflect your ability to tune, and that is dependent on good loading technique. None of us can predict what the rig will do from an undersampled charge ladder, so make sure you plan your next tests with a focus on your end goal. Pick the best groups and watch the speed too.

If there is no significant group size difference between two different loads, but there is a difference in their velocity stats, I would still encourage you to test both at 600 to learn the value of those stats. Good Luck.
 
@Stan Taylor nailed it...

The velocities on your chart are single samples and are important but cannot get us all the way to the goal.

Yes, your groups are just as important as your velocities when testing at short range and extrapolating to longer ranges.

Tuning a gun is done because it makes a very big difference. External ballistics and group performance at range are non-linear and that regression straight line on the plot is just one example of this. When you tune your rig, the recipe includes lots of parameters but let's make this a shorter talk and stick to the simplified version that says you are searching for the correct charge and depth.

The speed and charge relationship is basically linear but those waves are what we are searching for in terms of tuning. The impacts and groups are similar in that they don't respond to incremental changes in powder in a linear way. We are trying to find the advantages of being at the right speed, with a charge that gives the best groups, and if at all possible the best velocity stats in case we want to use that load at unknown distances.

A tight group at any distance is great, but they sometimes don't align to the best velocity stats. Make no mistake about it, when you see a great group at 100/200 with poor velocity stats, it generally falls apart at distance. The opposite is also true, when you see a tight group at 100/200 and it also has great velocity stats, it generally holds together at distance.

If you are trying for 600 yards, then play with the ballistics calculators and you will find that your velocity stats just need to be decent to keep the hypothetical vertical under control. In reality, there are many accomplished shooters that don't own a chrono and don't care about their velocity stats cause their groups are good. If you push a good 600 yard load to 1000 with a velocity stat that isn't state of the art, don't expect to play in the big leagues.

You can do fine with a decent velocity stat and short range testing to get out to 600. Your group testing will typically reflect your ability to tune, and that is dependent on good loading technique. None of us can predict what the rig will do from an undersampled charge ladder, so make sure you plan your next tests with a focus on your end goal. Pick the best groups and watch the speed too.

If there is no significant group size difference between two different loads, but there is a difference in their velocity stats, I would still encourage you to test both at 600 to learn the value of those stats. Good Luck.
I understand that a single sample ladder test is of questionable value. But I've not seen much discussion about how many shots are required for the data to be, truly valuable. I personally like 5 shots, then I show them in a box-plot and use the average for that charge wt. as the value for the ladder. I like the box plot because it is easy to see the variation in velocity for each individual charge wt. But often I still can't find what I would consider "flat" spots.
 
That’s what I thought this whole forum was about
 

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I understand that a single sample ladder test is of questionable value. But I've not seen much discussion about how many shots are required for the data to be, truly valuable. I personally like 5 shots, then I show them in a box-plot and use the average for that charge wt. as the value for the ladder. I like the box plot because it is easy to see the variation in velocity for each individual charge wt. But often I still can't find what I would consider "flat" spots.
Don’t get too hung up on “flat”. Imagine how it would be if there was nothing but perfect linear behavior in the internal ballistics of both the pressure and the barrel harmonics.

Since there are some departures from that perfect linear behavior in terms of combustion and the structural responses of everything else, we just look for the “best” ones we can get and move along.

Flat can mean anything from less of a climb, to actually flat as in no increase for a few tenths as well as a low SD in that spot. Many times we don’t get that ideal giant flat spot, but it should be obvious where the better spots are compared to the worst ones. An inflection in the average that shows an advantage at least 0.3 grains wide is often as good as it will get.
 
I would look at 33.9... Seems to be near a node to me, as 33.8 was lower, 34 was about the same height from the line. The one at 34.2 was much lower..
 
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So I just started to try to develop a load with H4350 for my Dasher because I have more of that than Varget or R15. I shot the horizontal row with charges increasing 0.2 Gr from 33.6 Gr to 35.2 Gr w/ Berger 108's seated about .015" off the lands. I wished I'd loaded a 35.4 Gr. charge but I'm not sure I could have seated the bullet to length with that much powder. I felt good about all the shots and there was almost no wind. The aim points were the intersection of the grid lines closest to the respective hole. There were no pressure indications. I've heard about looking for speed flat spots and impact flat spots and I'm not sure where to go next. What would you do next and why? Thanks for taking time.

I’d concentrate on the 34.x loads as well as the top load you used.

I ran 36.0 grains of h4350 in my Dasher with 105s and 107s. Use a long drop tube and tap the case a little and it should settle in there.
 
Before I went much further I'd load one at H4350 .006" past first touch (into the lands) and check for pressure and velocity. Back off a bit if needed to be around 2950 fps.

If that works I would do 3-shot groups .006" IN, .015" out, and .020" out.

Honestly, I don't think the one shot ladders are particularly useful. Good barrels with a Dasher will probably shoot well at a variety of powder charges.

There are a lot of people who have won a lot of matches with 105-108s moderately in the lands at around 2950 fps. I am presuming you have a quality barrel.
 
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