gregmark24
Well-Known Member
Yes. JKL Precison for $35. Compared my LabRadar to his new Garmin Xero and velocities were usually within 5fps or less. Garmin's SD's were significantly lower for 3 shot groups than LabRadar. LabRadar and Excel agree
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6.5 PRC Powder Charge/Velocity Ladder Test. No Flat Spot
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blksno
Well-Known Member
So glad to see Hornady come out with the Podcast. Here's the photo Miles sent me 5-6 years ago showing his testing...I abandon the "Flat Spot Theory" immediately.
35 repeated tests
100 repeated tests
Troutslayer2
Well-Known Member
- Joined
- May 28, 2010
- Messages
- 780
i disagree with all of the velocity node haters having seen too many rifles shoot a relatively consistent velocity over a meaningful charge change. I find the middle of that charge and as long as it's where I want to be I'll load that. I do the same for jump. If a bullet shoots well within maybe a .03" range in jump I will try to find the middle of that too. This way I'm not chasing lands and it really doesn't matter if my process isn't that perfect with DTL or charge weight (within reason). Learned all of this from Saterlee and ain't no one gonna tell me it doesn't work because I'm hitting paydirt with about 20% of the bullets it used to take.
BrentM
Well-Known Member
Careful buddy, if your data sample is too large it gets noisy.
Justice1327
Well-Known Member
For what it is worth after 40 years of reloading and shooting 6-8000 rounds a year since retirement 10yrs ago. I think there is something to be said for the velocity, flat spot node.
I take all of my reloading manuals/websites and now GRT too, and I look at which reloading manuals uses the same powder with the same bullet weight and I average all of those loads out and that is what I start my load development with. For 308 sized cases I worked my way up in .3 grain increments. Smaller cases I do .2 gr and larger cases I do .5gr
I load one round in these increments up to a 1/2 - 3/4 gr over book max. I do this strictly to find where my pressure starts and that is my max load . I then go back to the middle of the charge weight range and load three rounds working my way up in the previously stated increments to my max load. I shoot 3 of these charge weights at a target looking for groups as well as capturing the velocity from each shot. Once I plot this out, I do look for a flat spot and I also look at the groups and compare each charge to what is listed on the plot map. Frequently I can find a velocity flat spot node that correlates with the smallest group and SD. I then go back and load five shots for each incremental area within that flat velocity node and look for groups as well as capturing the velocity again. If the results are similar, then I load in the middle of that charge weight of that velocity node. And then play with seating depth from where I normally start 20th off the lands. Once I find a good group here, I'll finish loading that charge weight and that COAL to finish breaking in my barrel and 100p of Brass. By this point in time your brass is on its way to being fire-formed to your chamber, and your barrel has probably sped up or getting close to speeding up. I then repeat the development test with the fire-formed Brass but I usually have to tweak it but it is really close from there. I now shoot out to 300yds, then 600 yards and then out to 1K then to 1400yds… if it holds together on previous attempts . for purely just hunting rifles, I keep it within 800yds for group testing. During this verification, I am also capturing velocity to verify my DOPE into true up my ballistics calculator. With all this said, I rarely struggle to find a load that doesn't shoot very well. I look at the velocity node, and I look at the targets to determine which is going to work best for me.
I take all of my reloading manuals/websites and now GRT too, and I look at which reloading manuals uses the same powder with the same bullet weight and I average all of those loads out and that is what I start my load development with. For 308 sized cases I worked my way up in .3 grain increments. Smaller cases I do .2 gr and larger cases I do .5gr
I load one round in these increments up to a 1/2 - 3/4 gr over book max. I do this strictly to find where my pressure starts and that is my max load . I then go back to the middle of the charge weight range and load three rounds working my way up in the previously stated increments to my max load. I shoot 3 of these charge weights at a target looking for groups as well as capturing the velocity from each shot. Once I plot this out, I do look for a flat spot and I also look at the groups and compare each charge to what is listed on the plot map. Frequently I can find a velocity flat spot node that correlates with the smallest group and SD. I then go back and load five shots for each incremental area within that flat velocity node and look for groups as well as capturing the velocity again. If the results are similar, then I load in the middle of that charge weight of that velocity node. And then play with seating depth from where I normally start 20th off the lands. Once I find a good group here, I'll finish loading that charge weight and that COAL to finish breaking in my barrel and 100p of Brass. By this point in time your brass is on its way to being fire-formed to your chamber, and your barrel has probably sped up or getting close to speeding up. I then repeat the development test with the fire-formed Brass but I usually have to tweak it but it is really close from there. I now shoot out to 300yds, then 600 yards and then out to 1K then to 1400yds… if it holds together on previous attempts . for purely just hunting rifles, I keep it within 800yds for group testing. During this verification, I am also capturing velocity to verify my DOPE into true up my ballistics calculator. With all this said, I rarely struggle to find a load that doesn't shoot very well. I look at the velocity node, and I look at the targets to determine which is going to work best for me.
Trout you are spot on with what I've learned is definitely The Load for me.
A little cushion with the bullet seating and powder charge, the center of the node, flat spot, sweet spot whatever you want to call it allows for enough forgiveness to promote consistency.
And to varying degrees that's what we all want.
I've been fortunate to have rifles built for the last 15-20yrs or so, and when correctly done it's daylight and dark as to how much less finicky they can be, overall. No matter the combo of components, within reason.
A little cushion with the bullet seating and powder charge, the center of the node, flat spot, sweet spot whatever you want to call it allows for enough forgiveness to promote consistency.
And to varying degrees that's what we all want.
I've been fortunate to have rifles built for the last 15-20yrs or so, and when correctly done it's daylight and dark as to how much less finicky they can be, overall. No matter the combo of components, within reason.
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Hugnot
Well-Known Member
Just started to view Hornady "velocity nodes" - lots on preliminary talk - long video.
Running my easy quick spread sheet(s):
I 4Xed the 7 data set to a 28 data set. The 7-point SD is 13.177, The 28-point SD is 13.147
Extreme spread is equal as both data sets are comprised of same data.
The big difference is the 24.337 mean difference with a 7-point set & 10.33 mean difference with a 28-point data set.
The 7-point data set used a T-Val of 2.262 & the 28-point data set used a T-Val of 2.042.
Velocity diffs matter when shooting longish ranges. Accuracy is a function of many variables. Mass production of 1000's of rounds of ammo that might shoot well in some rifles but not others is usual. Factory recalls occur.
Loads that produced the 7-point data shot very well when the Magneto bayonet was removed, like under .5 inches & under 3 inches at 300. Components are pricy. Good ammo prep is needed & I do my best like turning necks, consistent neck tension, powder weighing & other.
I will endure the Hornady Pod Cast & appreciate being advised of it,.
Running my easy quick spread sheet(s):
I 4Xed the 7 data set to a 28 data set. The 7-point SD is 13.177, The 28-point SD is 13.147
Extreme spread is equal as both data sets are comprised of same data.
The big difference is the 24.337 mean difference with a 7-point set & 10.33 mean difference with a 28-point data set.
The 7-point data set used a T-Val of 2.262 & the 28-point data set used a T-Val of 2.042.
Velocity diffs matter when shooting longish ranges. Accuracy is a function of many variables. Mass production of 1000's of rounds of ammo that might shoot well in some rifles but not others is usual. Factory recalls occur.
Loads that produced the 7-point data shot very well when the Magneto bayonet was removed, like under .5 inches & under 3 inches at 300. Components are pricy. Good ammo prep is needed & I do my best like turning necks, consistent neck tension, powder weighing & other.
I will endure the Hornady Pod Cast & appreciate being advised of it,.
Are those the only powders you have? I can get to 3100 with VV N565.
Hugnot
Well-Known Member
Sounds great - any data?
Hugnot
Well-Known Member
I usually start out at a near max pressure level that will not make primer pockets expand.
I shoot lots of .204R ammo:
These loads are close to max. 10 samples were taken using CFE223 & only 5 samples were taken using IMR8208. Accuracy was better with IMR 8208. Both were easy to dispense thru powder measure - random weight samples were taken. The CFE 223 has a greater density than IMR 8208. Both filled case to same approximate level. My preference is IMR 8208 because of high temperatures boosting pressures. Many rounds using IMR 8208 shot at temps. over 85.
For the 6.5-06 I get 2832 fps average for 57.5 gr. Staball HD. The VV online manual for 6.5-.284 Norma loads with 140 ELD bullets & VV N565 gives 2881 fps using 54.3 grains- 49 fps more. No pressure data for VV loads. A 59.6 grain load of Staball HD, with a 140-grain bullet in the 6.5PRC gives 2950 fps with 60.8K PSI. Possibly, .5 gr. more or 58.0 gr. Staball HD in the 6.5-06 would get me over 2900 fps but pressures only could estimated. I would not try to get 3,100 fps with 140's out of a 6.5-06
I shoot lots of .204R ammo:
These loads are close to max. 10 samples were taken using CFE223 & only 5 samples were taken using IMR8208. Accuracy was better with IMR 8208. Both were easy to dispense thru powder measure - random weight samples were taken. The CFE 223 has a greater density than IMR 8208. Both filled case to same approximate level. My preference is IMR 8208 because of high temperatures boosting pressures. Many rounds using IMR 8208 shot at temps. over 85.
For the 6.5-06 I get 2832 fps average for 57.5 gr. Staball HD. The VV online manual for 6.5-.284 Norma loads with 140 ELD bullets & VV N565 gives 2881 fps using 54.3 grains- 49 fps more. No pressure data for VV loads. A 59.6 grain load of Staball HD, with a 140-grain bullet in the 6.5PRC gives 2950 fps with 60.8K PSI. Possibly, .5 gr. more or 58.0 gr. Staball HD in the 6.5-06 would get me over 2900 fps but pressures only could estimated. I would not try to get 3,100 fps with 140's out of a 6.5-06
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Munch
Well-Known Member
Having been at the reloading bench 50+ years now...the biggest advancement we have at our disposal is technology and reams of data it produces. And therein lies, the rabbit hole (and the rabbit hole has ALWAYS been there!).
To crunch the data, we use statistical models. And regardless of the subject matter being analyzed, ladder testing, rush hour traffic, weather, the size of the sample population is the underlying key to either gaining confidence in or loss thereof in one's hypothesis regarding the data. And one professor's comment from a statistics class I had in 1974 sticks with me to this day...."using statistics, one can offer a persuasive argument on both sides of a debate."
While larger sample sizes (data collected from the bench and shots down range in this case) may prove nodes as a statistical anomaly, what the data can and should drive is our confidence in a given load. And ultimately, that is the upside of statistics...to gain confidence in a particular theory; not necessarily to prove or disprove that same theory.
And ultimately, my confidence level for a specific load may be totally different than yours. And that is perfectly fine. I am not taking your shot, and you are not taking my shot.
To crunch the data, we use statistical models. And regardless of the subject matter being analyzed, ladder testing, rush hour traffic, weather, the size of the sample population is the underlying key to either gaining confidence in or loss thereof in one's hypothesis regarding the data. And one professor's comment from a statistics class I had in 1974 sticks with me to this day...."using statistics, one can offer a persuasive argument on both sides of a debate."
While larger sample sizes (data collected from the bench and shots down range in this case) may prove nodes as a statistical anomaly, what the data can and should drive is our confidence in a given load. And ultimately, that is the upside of statistics...to gain confidence in a particular theory; not necessarily to prove or disprove that same theory.
And ultimately, my confidence level for a specific load may be totally different than yours. And that is perfectly fine. I am not taking your shot, and you are not taking my shot.
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Hugnot
Well-Known Member
I try to get reasonable brass life and that means staying within pressure limits that will not exceed elastic limits of brass. Most pressure data is now shown as psi (pounds per square inch), older data was shown as CPU (copper units of pressure):
https://en.wikipedia.org/wiki/Copper_units_of_pressure.
A conversion made be done by:
More info on this:
calculator.academy
This is a regression analysis.
Just guessing, the elastic limit might vary on brass quality and the degree of work hardening the brass head is subjected to. I think pressures in the low to mid 60K PSI range might be the limit. Certain brass like small primer Lapua 6.5X47 brass might be able to get close to 70K PSI.
Essentially, the important thing is how good does it shoot? Assuming careful loading is done to assure consistency & uniformity, a normal distribution workup will determine expected velocity ranges using a relatively small sample, like 1%-2% or less. This may be done using the "Students T" analysis, common in stats.
This is important for long range shooting. For example, using the Hornady 4DOF calculator with the 6.5 140 gr ELDM bullet having a velocity hi/low of 10.3 fps compared to a hi/low of 34.0 at 1000 yards. 100 yard zero, drop measured in inches.
2950 fps 261 inches
2916 fps 268 inches
Enough to drop below the X ring or even 10 ring.
If 1000's of rounds needed be mass produced for military use, a good data normal distribution workup might produce an average high velocity range and an average low velocity range like 10.3. At 1000 yards the average drop measurement would be:
2950 fps 261 inches
2940 fps 263 inches
I never produced military ammo but shot 1500 -2000 rounds per year of which were 30 % at 600 & 1000 yards and a good stat workup using a normal distribution would flag any ammo issues prompt changes for better scores. Like go for small diffs in hi/low averages. Other factors like temperatures & elevation need to be considered.
A good day at the rodent grounds might shoot up more than 400 rounds and having ammo with consistent velocities kills more of them.
https://en.wikipedia.org/wiki/Copper_units_of_pressure.
A conversion made be done by:
More info on this:
CUP ↔ PSI Calculator - Calculator Academy
Enter the total CUP into the calculator to determine the equivalent PSI.
calculator.academy
Just guessing, the elastic limit might vary on brass quality and the degree of work hardening the brass head is subjected to. I think pressures in the low to mid 60K PSI range might be the limit. Certain brass like small primer Lapua 6.5X47 brass might be able to get close to 70K PSI.
Essentially, the important thing is how good does it shoot? Assuming careful loading is done to assure consistency & uniformity, a normal distribution workup will determine expected velocity ranges using a relatively small sample, like 1%-2% or less. This may be done using the "Students T" analysis, common in stats.
This is important for long range shooting. For example, using the Hornady 4DOF calculator with the 6.5 140 gr ELDM bullet having a velocity hi/low of 10.3 fps compared to a hi/low of 34.0 at 1000 yards. 100 yard zero, drop measured in inches.
2950 fps 261 inches
2916 fps 268 inches
Enough to drop below the X ring or even 10 ring.
If 1000's of rounds needed be mass produced for military use, a good data normal distribution workup might produce an average high velocity range and an average low velocity range like 10.3. At 1000 yards the average drop measurement would be:
2950 fps 261 inches
2940 fps 263 inches
I never produced military ammo but shot 1500 -2000 rounds per year of which were 30 % at 600 & 1000 yards and a good stat workup using a normal distribution would flag any ammo issues prompt changes for better scores. Like go for small diffs in hi/low averages. Other factors like temperatures & elevation need to be considered.
A good day at the rodent grounds might shoot up more than 400 rounds and having ammo with consistent velocities kills more of them.
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gregmark24
Well-Known Member
Fascinating. I had no idea my original post would create this level of good data, good opinions; and variety. All: thank you. Nobody has replied yet to the carbon barrel--I would think that his 6.5 PRC with a carbon-wrapped barrel would damp out harmonics. Hugnot--interesting you would bring up the 140 ELDM. I'm doing all my workups right now on the 243, and my next project is my 6.5 CM. Small primer Lapua, Fed 205M, H4350, and 140 ELDM's. I will try a different methodology here, with the Hornady guys' statements fresh in my mind: of no velocity nodes when shooting 100 rounds per charge within a ladder, and that powder and bullets make the biggest difference, with powder charge and seating almost a don't care. I'm still going to do a standard ladder test with new brass, and then repeat it with once-fired. If the velocity curve of average velocity per charge has nodes, and both new/once-fired agree (as they did with my 243), I'm sticking with the same process as with the 243, where I had a node around 38.6 gr at approx 2800 ft/sec. If the curves have nodes at different spots, or both curves are linear with no flat spots, I'm adopting the Hornady model. Ie, pick a muzzle and 1000 yd velocity I like, making sure it is 1 to 1.5 grains off the max charge (pressure signs), do 5 rounds at a few seating depths at a charge I've picked, pick that charge and seating depth, and qualify at 100 yds with 3 shots per target on 7 targets, and combine all the data as if it were one set (mathematically). Adjust the scope, and take the shots farther out.
swandme686
Member
I have 4 6.5 PRC 3 of the 4 have Carbon Bbls
2 Factory Savage 110 with factory 24" Proof
Bbls 1 with a MDT Hnt 26 folder
1 in an MDT XRS Chassis
1Tikka T3x in a MDT ACC chassis 26" Bartlien
Carbon
1 Tikka T3x 28" Bartlien Heavy Senduro
All shoot well with the same load with Hornady 140 ELDM. All sub 1/2 in at 100
All have great performance I only did load development with this bullet on one the first 2 rifles and they just worked beautifully in all 4 so I counted my blessings and moved to trying drive myself insane with experimenting
With every other 6.5 bullet I could get my hands on
beginning in fall off 2020 My quest for the best possible load found me investing in Hornady, then Nosler, then Peterson and finally what I wanted all along Lapua brass, and 1000 of each of the following bullets ( so when I found the holy grail load every thing would be from the same lot…)
In short well ok long but it was a great learning experience and here is what I learned
First to note I like speed ! The faster the bullet get to the target the less time the wind has to push it around
My goal was to bump into the max speed for PRS of 3200 with what ever load I would land on ….
Berger 130, 140 hybrid 140 hunter ( 144 best of the Berger ) 156 LR hybrid
Hornady 135 & 153 Atip 140 & 147 ELDM
143 ELDX
Lapua 136 Senar II
Sierra 142 TMK and 150 MK
Powder tested RL 23 RL26 Sta-Bal 2 variants
and the new Gucci IMR powders and a couple more I would have to refer to my notes
and WRL, WLRM, Fed LR, Fed LR match,
Fed LRMag Match
What's interesting matches with my previous experiences with 6mm creedmore and recent experiences with 6mm ARC
Each Combo I tried I found a fantastic load for each rifle but ….
That load did not perform nearly as well in the other sibling rifles except….***
144 Berger in Lapua brass with 57.2 RL26 from the 28" pipe was the best consistent
Group of all tested yielding at .25ish groups at 100 but in the other rifles it opened up to 1 in or more
The Sierras didn't glow in any combo best was .77
The Lapua 136 Scenar II were also a one rifle wonder
In the end *** the ELDM and ELDX 140 143 and 147 shoot very well in every rifle
Best group is .370 but the worst is still sub 1/2 in at 100 from all 4 rifles
The go to load ended up to be
140 ELDM with 57.5 RL26 in a Lapua case
w Fed LR match and flies at 3197 ish parents Lab Radar ( recently tested with the new Garmin Xero ) plus or minus 2 FPS
But the point of all those words was to share that I had 2 solid nodes with every test I did
One twords the top where I like to run and one about 150 to 200 FPS slower
All my tests are run .3 grain ladders
I load both a batch of Max and a batch of the step down ( I have found loads that perform
Well here in Wisconsin at 1637 elevation
at Max do not perform will at Raton NM or Logan Utah, SantaFe or other higher elevations ( that's a novel for another day )
I have been blessed with many tools to pursue that perfect load and in the end
Red may not be the choice for winning
a bench rest match with one tiny hole
But when you have multiple rifles it makes my very happy to grab one ammo tote and 4 rifles that I know will ring steel all day
