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What kind of Extreme spread is acceptable
- Thread starter Jevyod
- Start date
Oliver Sudden
New member
With smokeless that is OK, with black powder cartridge I get 10 or less.
Doublehelix3216
New member
Pistol or rifle? You will get higher ES values with pistol rounds that use lower weights of powder (obviously).
Depending on the powder, with pistol rounds, I like to see less than 50, and honestly, ES values under 40 are pretty danged good for me, especially when using a powder drop and not weighing each load.
Depending on the powder, with pistol rounds, I like to see less than 50, and honestly, ES values under 40 are pretty danged good for me, especially when using a powder drop and not weighing each load.
If it was really cold, powder and primers might not perform as well as they do in more hospitable weather.
It doesn't take much to cause an extra 25 fps drop in measured velocity.
I experimented with using magnum large rifle primers in my .30-06 loads in really cold weather. The chronograph measurements increased by 12 fps and improved the standard deviation and reduced the extreme spread. Those results were measured with temps just below 20 degrees F.
It doesn't take much to cause an extra 25 fps drop in measured velocity.
I experimented with using magnum large rifle primers in my .30-06 loads in really cold weather. The chronograph measurements increased by 12 fps and improved the standard deviation and reduced the extreme spread. Those results were measured with temps just below 20 degrees F.
Uneven velocities may be due to the powder, the charge, primer seating uniformity, neck prep etc. If you are confident in the case prep it could very well be the powder and charge. I am doing some testing on a new .260 setup and the same loads that shoot great in my 26 inch barreled match gun gave inconsistent results in the same brand/twist barrel in a 24 inch setup
Don Fischer
New member
My though is if the rifle shoot's well enough for me, I could care less about ES.
My though is if the rifle shoot's well enough for me, I could care less about ES.
quoted for truth. ES can have a major effect on the 1000 yard shooter but for the typical plinker/hunter who rarely shoots beyond 300 the effect would be negligible
A quote from Precision Rifle Blog:
“Regarding available ammunition types, a Standard Deviation (SD) of 20 fps is considered relatively poor consistency, and is generally representative of mass produced factory ammo. 15 fps is considered better than average for factory produced ammunition, but still substandard for those who handload their own ammunition. 10 fps or less SD is typically the goal of most handloaders, and very few commercially available ammo suppliers are capable of producing ammo with SD’s under 10 fps.”
The author, Cal Zant, is talking about SD but it is a descriptor of ES. An SD of 20 means 68% of your shots fall between +or - 20 FPS of your mean. That is a 40 FPS spread. It also means that 95% of your shots fall within 80 FPS ES. There are many threads describing the necessary precision required to get to single digit SDs. He further states:
"It’s relatively easy for a reloader to produce ammo with an SD of 15 fps, but you have to be meticulous and use good equipment if you want to wrestle that down into single digits. I have a friend who has handloaded ammo for his 6.5×47 Lapua and 338 Lapua with an SD of 3 fps across 10 shot strings! I’ve witnessed it with my own eyes, and he’s done on multiple occasions. 3 fps is the lowest SD I’ve ever heard of, but it takes exponentially more effort to creep down into those lower numbers."
I recently shot a 25 shot group with a SD of 6.8. The ES was 30. In the authors example of an SD of 3 the ES for 95% of the shots would be within 12 FPS. This is the absolute best you could hope for, It appears you are flirting with an SD of 15. You have 2 choices, get to work, or enjoy your efforts and shoot.
“Regarding available ammunition types, a Standard Deviation (SD) of 20 fps is considered relatively poor consistency, and is generally representative of mass produced factory ammo. 15 fps is considered better than average for factory produced ammunition, but still substandard for those who handload their own ammunition. 10 fps or less SD is typically the goal of most handloaders, and very few commercially available ammo suppliers are capable of producing ammo with SD’s under 10 fps.”
The author, Cal Zant, is talking about SD but it is a descriptor of ES. An SD of 20 means 68% of your shots fall between +or - 20 FPS of your mean. That is a 40 FPS spread. It also means that 95% of your shots fall within 80 FPS ES. There are many threads describing the necessary precision required to get to single digit SDs. He further states:
"It’s relatively easy for a reloader to produce ammo with an SD of 15 fps, but you have to be meticulous and use good equipment if you want to wrestle that down into single digits. I have a friend who has handloaded ammo for his 6.5×47 Lapua and 338 Lapua with an SD of 3 fps across 10 shot strings! I’ve witnessed it with my own eyes, and he’s done on multiple occasions. 3 fps is the lowest SD I’ve ever heard of, but it takes exponentially more effort to creep down into those lower numbers."
I recently shot a 25 shot group with a SD of 6.8. The ES was 30. In the authors example of an SD of 3 the ES for 95% of the shots would be within 12 FPS. This is the absolute best you could hope for, It appears you are flirting with an SD of 15. You have 2 choices, get to work, or enjoy your efforts and shoot.
m&p45acp10+1
New member
I test accuracy before I ever put anything over the chronograph. A load that shoots poorly, yet has the same velocity shot after shot is still a load that shoots poorly. I have a couple of loads in my 6.5 Creedmoor that shoot sub half MOA. If I go to take them to the 1K yard shooting range I will chronograph to get an average velocity to work with then.
I am not chasing a magic number. I want loads that put the bullet where the cross hairs of my scope are time and again.
I am not chasing a magic number. I want loads that put the bullet where the cross hairs of my scope are time and again.
Jevyod asked:
What kind of Extreme spread is acceptable?
Whatever is acceptable to you.
As you fired each round through the chronograph, did you note where it impacted the target?
Also, are the velocities in your string clustered around a particular velocity with a single outlier creating the spread, or is the distribution of velocities pretty well spread out? In statistical terms, what was your mean, median, mode and what was the standard deviation of the string?
If the velocity differences are not impacting your point of impact and they were pretty well distributed throughout your range then I would ignore spreads of 40 or 65 fps.
If you had nine rounds all within 10 fps of one another and then one that was 55 fps out, AND the 55 fps outlier hit the target well away from the other rounds than you might want to throw some charges to the pan on your scale and see if you need to work on your powder measure, otherwise ignore it.
I throw all my charges to the scale and then trickle up to weight so I know my charges are consistent and even so I once loaded a string of 223 Remington rounds that produced an extreme spread of 254 fps. I attribute the spread to the fact the cheap FMJs I was shooting had significant variability in dimensions. Still, at 100 yards, all the rounds were within a 1.5 inch circle and I was firing offhand, not from a bench, so I said that was good enough for what I needed to do.
OzeanJaeger
New member
It has been my experience that the tightest groups "magically" alight on the velocity nodes. If a change in 3 or 4 grains of powder creates a consistent velocity does it not stand to reason that they're going to produce almost the same barrel vibration all things being equal?
I can't remember ever finding a node that offered worse precision than a yo-yo load and velocity with high SD/ES/.
If you're a 6PPC shooter running a 1-(10-14) twist @ 300 yards, or a hunter who is zeroing his deer rifle, it doesn't matter, and you're not even worrying about velocity. My guess is that if you threw a chrony on that bug-hole, group or score load you would find it's in the middle of a velocity node. Now, I don't say that's what you're going for or even care, but there you have it.
Those of us who shoot matches from improvised positions out to 1,400 yards care a great deal about SD/ES, but from that when I'm tuning a deer rifle I start in the same place. No, I'm not shooting more than 400 yards, but I can find the load in half the cartridges when I shoot a velocity ladder first. The principals don't go away just because you're using the rifle for something else. Precision is precision.
I can't remember ever finding a node that offered worse precision than a yo-yo load and velocity with high SD/ES/.
If you're a 6PPC shooter running a 1-(10-14) twist @ 300 yards, or a hunter who is zeroing his deer rifle, it doesn't matter, and you're not even worrying about velocity. My guess is that if you threw a chrony on that bug-hole, group or score load you would find it's in the middle of a velocity node. Now, I don't say that's what you're going for or even care, but there you have it.
Those of us who shoot matches from improvised positions out to 1,400 yards care a great deal about SD/ES, but from that when I'm tuning a deer rifle I start in the same place. No, I'm not shooting more than 400 yards, but I can find the load in half the cartridges when I shoot a velocity ladder first. The principals don't go away just because you're using the rifle for something else. Precision is precision.
Same SD of 10fps. One is a light load of 1500fps. The other is a hotter load of 2500fps. Which has better speed consistence? So why SD of 10fps is always better than SD of 20fps? Shouldn't muzzle velocity be considered?
Load with better speed consistence does not always produce better groups, because there are more factors involved. If so, why fixate on SD, or ES? You just want to shoot a good group, do you not?
I chronograph my loads, because I want to know its speed. I need to record mutiple shots so that I can calculate the average. Since the data is already there, why not the SD? That figure is there mostly because it is there. I don't really get stuck with it.
If I have to come up with a criteria, SD / mean < 1% with sample size of at least 10 is good enough for me.
Oh, what's the accuracy of a cheapy chronograph?
-TL
Sent from my SM-G930T using Tapatalk
Load with better speed consistence does not always produce better groups, because there are more factors involved. If so, why fixate on SD, or ES? You just want to shoot a good group, do you not?
I chronograph my loads, because I want to know its speed. I need to record mutiple shots so that I can calculate the average. Since the data is already there, why not the SD? That figure is there mostly because it is there. I don't really get stuck with it.
If I have to come up with a criteria, SD / mean < 1% with sample size of at least 10 is good enough for me.
Oh, what's the accuracy of a cheapy chronograph?
-TL
Sent from my SM-G930T using Tapatalk
Last edited:
OzeanJaeger
New member
It's actually really, really good, because electronics have become so cheap. Even a Caldwell uses a high speed processor and boasts a +/- 0.25% accuracy.