What is an acceptable standard deviation for rifle hand loads vs factory rifle loads

[Remtac]

Went out testing two new loads today with the new G2 chronograph.


First was cal .243 with H-4350(42g powder) 95g Berger VLD target
Standard deviation was 10.8 feet per second .




Second was cal .243 with reloader15 (38g powder) 95g Berger VLD target
With a standard deviation of 7.9 feet per second .

 

[Ltbull01]

10 fps?! That's pretty damn good for handloads. If it's accurate, I'd virtually stop right there!! I rarely fire factory so wouldn't know about SD there but generally find it to be quite wide!!

 

[grouch]

Unless you're doing really long range bench rest standard deviation of velocity is some distance down your list. It very often doesn't relate to the achieved accuracy.
grouch

 

[Remtac]

10 fps?! That's pretty damn good for handloads. If it's accurate, I'd virtually stop right there!! I rarely fire factory so wouldn't know about SD there but generally find it to be quite wide!!

Getting decent groups I guess .413" at 100 yards . With the reloader 15 powder I got even better at 7.9 fps standard deviation

 

[Ganderite]

Ordinary handholds for me run an SD of 25 to 35.

A full accuracy load, with weighed cases and powder charges, prepped brass run just under 10. Any single digit SD is fantastic.

I like that you are testing 10 rounds. That will have some statistical validity.

That said, that does not mean the ammo will be accurate. That depends on finding the right load for the rifle (harmonics, etc.)

A good load cannot be seen at 100 yards (although a bad load can). A good load is what you can see at 500 to 1000 yards.

Here is a good 500 yard test of 20 shots. under 2" vertical.

 

[Remtac]

Ordinary handholds for me run an SD of 25 to 35.

A full accuracy load, with weighed cases and powder charges, prepped brass run just under 10. Any single digit SD is fantastic.

I like that you are testing 10 rounds. That will have some statistical validity.

That said, that does not mean the ammo will be accurate. That depends on finding the right load for the rifle (harmonics, etc.)

A good load cannot be seen at 100 yards (although a bad load can). A good load is what you can see at 500 to 1000 yards.

Here is a good 500 yard test of 20 shots. under 2" vertical.

That's nice grouping at 500 yards . Yes most of my shooting is done at 1000 yards on a IPSC steel target . Now back to the standard deviation topic , my girlfriends father is a professor at a university, he wrote a book on statics and he claims for a more accurate standard deviation that I should shoot a 30 shot string .




I can't read the book it's in Spanish but I guess I will take his word for it .

 

[Suputin]

Unless you're doing really long range bench rest standard deviation of velocity is some distance down your list. It very often doesn't relate to the achieved accuracy.
grouch

THIS! Standard deviation is not a goal. Accuracy is the only goal worth pursuing. Velocity standard deviation is only of any importance at very long range where it can produce vertical stringing.

 

[bigedp51]

Here is a good 500 yard test of 20 shots. under 2" vertical.

Ganderite

I have a question............why were you shooting at your watch and why didn't you hit it. Was this a attempt to make time fly?

 

[Ganderite]

"Why were you shooting at your watch and why didn't you hit it?"

I needed something to aim at. Black crosshair on a black target is hard to see.

I prefer a fly on a white target. One of his balls is a perfect aim point for someone of my skill level, but the best I can get with that is a one-shot group....

Actually, the procedure was to fire a couple fouling shots at an aiming mark, and then place a piece of paper where they hit to "catch" the next 20 shots.

 

[Remtac]

THIS! Standard deviation is not a goal. Accuracy is the only goal worth pursuing. Velocity standard deviation is only of any importance at very long range where it can produce vertical stringing.

Well to me a low standard deviation tells me how consistent my hand loads are . A low standard deviation will give me a better probability of hit percentage then a high one . there are many factors in long range shooting not just how accurate you can aim .to me it's a goal ,I'd rather have my 7.9 fps then 30fps any day




Look at the difference between 10fps and let's say 20-30fps . I believe it not only affects at long range but imagine at 100 yards you have a Bullet that comes out your muzzle 30fps faster then the previous 4 , well I think the point of impact on that bullet will be different then the other 4 even at 100 yards . Then multiply that by 10 for a 1000 yards , it could mean the difference between a kill or a miss , so yes I do believe it should be another of many goals .

 

[Ganderite]

How many shots required to be valid sample?

10 is better than 5

20 is better than 10

And yes, 30 is even better.

But in the real world we have the cost of ammo and the cost of barrel life.

I typically test 5 different loads at a time, in 0.3 gr increments. I shoot for accuracy, with chony results (SD and ES) being an interesting by-product.

When load developing I shoot 10 shots, so as to see if there are fliers. When I think I have "the" load, I test 20 rounds, to see what I actually have.

30 might be better, but I have to deal with barrel heat and wind shifts over the string. Wind is minimised by shooting quickly. The 20 shot group above was shot in less than 30 seconds. No wind, but lots of heat!

I was not the trigger puller.

 

[Remtac]

10 is better than 5

20 is better than 10

And yes, 30 is even better.

But in the real world we have the cost of ammo and the cost of barrel life.

I typically test 5 different loads at a time, in 0.3 gr increments. I shoot for accuracy, with chony results (SD and ES) being an interesting by-product.

When load developing I shoot 10 shots, so as to see if there are fliers. When I think I have "the" load, I test 20 rounds, to see what I actually have.

30 might be better, but I have to deal with barrel heat and wind shifts over the string. Wind is minimised by shooting quickly. The 20 shot group above was shot in less than 30 seconds. No wind, but lots of heat!

I was not the trigger puller.

Yes you are right , what I would do is shooting in -5 temperature like I did yesterday actually it as -8 after every 5 shots I would wait a full 2 minutes before shooting another 5 shots. I'm also curious on how much wind affect has on muzzle velocity on a bullet travelling its first 5-10 feet ?

 

[RonR]

Well to me a low standard deviation tells me how consistent my hand loads are . A low standard deviation will give me a better probability of hit percentage then a high one . there are many factors in long range shooting not just how accurate you can aim .to me it's a goal ,I'd rather have my 7.9 fps then 30fps any day
....so yes I do believe it should be another of many goals .

Nicely stated Remtac. I am a believer in the process part of reloading and SD is an indicator of how well the "process" is doing. (Process in this situation is the care and attention to every part from components, to prep, to the tools and methods used.) I prefer knowing that the process is highly repeatable and when it's not it drives me nuts.

I am certainly not a stat's guru by any stretch but min sample size for any validity was 7 if I remember from a six sigma quality course I had to take. The more samples the better and 10 is solid. That sample size will tell you lots.

FWIW

Regards
Ronr

 

[RonR]

I prefer a fly on a white target. One of his balls is a perfect aim point for someone of my skill level, but the best I can get with that is a one-shot group....

That's funny..."Eyebrows off a gopher" is one phrase that comes to mind but this is much better Ganderite!

lol

Regards
Ronr

 

[Ganderite]

Well to me a low standard deviation tells me how consistent my hand loads are . A low standard deviation will give me a better probability of hit percentage then a high one . there are many factors in long range shooting not just how accurate you can aim .to me it's a goal ,I'd rather have my 7.9 fps then 30fps any day




Look at the difference between 10fps and let's say 20-30fps . I believe it not only affects at long range but imagine at 100 yards you have a Bullet that comes out your muzzle 30fps faster then the previous 4 , well I think the point of impact on that bullet will be different then the other 4 even at 100 yards . Then multiply that by 10 for a 1000 yards , it could mean the difference between a kill or a miss , so yes I do believe it should be another of many goals .

I have developed loads for 1000 yard shooting for quite a few rifles. A low SD is nice, but is not a significant issue in the real world. I would shoot off sandbags at 1000 yards, using test ammo in 0.3 gr increments. What mattered was that 45.3 shot the flattest group and 46.1 shot the tallest group. It was quite common, if not usual, for the best shooting ammo in a given rifle to have a poorer SD than than the ammo that shot the big group.

This is because of barrel harmonics:

A barrel is vibrating the muzzle up and down as the bullet leaves.

The barrel may be on the way up as the bullets leave; or on the way down.

Some bullets are faster than others - unless the ES is zero.

If the barrel muzzle is moving down as the bullet leaves, the slow bullets will be aimed a bit lower, making the group even worse.

If the barrel muzzle is moving up as the bullet leaves, the slow bullets will be aimed a bit higher, making the group better than otherwise.

It is more important to launch with the barrel in the correct mode than it is to get the lowest SD.

I make ammo that shoots the best group, and the SD it what it is. If I check it, it is just because the Chrony automatically spits out the number.

Cue biged51 and some nice graphics,

 

[Suputin]

I have developed loads for 1000 yard shooting for quite a few rifles. A low SD is nice, but is not a significant issue in the real world. I would shoot off sandbags at 1000 yards, using test ammo in 0.3 gr increments. What mattered was that 45.3 shot the flattest group and 46.1 shot the tallest group. It was quite common, if not usual, for the best shooting ammo in a given rifle to have a poorer SD than than the ammo that shot the big group.

This is because of barrel harmonics:

Yep, I don't give a toss about SD. There are so many other things going on between you and a distant target that SD is a minor issue.

 

[J996]

Fire off 20 or 30 rounds at 300 yards. That will show you if your load is ready to go for competition or if it needs more work.

 

[RonR]

Ganterite, Saputin for myself I agree, real world results trump any statistics. Once the right load is achieved I just want to keep the loads repeating consistently. I got into it with Ron AKA over that and then just quit it because it was too frustrating. Your experience on the 303br long distance Ganderite is enlightening for myself.

Best Regards
Ronr

 

[Remtac]

Nicely stated Remtac. I am a believer in the process part of reloading and SD is an indicator of how well the "process" is doing. (Process in this situation is the care and attention to every part from components, to prep, to the tools and methods used.) I prefer knowing that the process is highly repeatable and when it's not it drives me nuts.

I am certainly not a stat's guru by any stretch but min sample size for any validity was 7 if I remember from a six sigma quality course I had to take. The more samples the better and 10 is solid. That sample size will tell you lots.

FWIW

Regards
Ronr

Good stuff

 

[Remtac]

Yep, I don't give a toss about SD. There are so many other things going on between you and a distant target that SD is a minor issue.

The lower your SD is the more accurate your average muzzle velocity will be for your ballistics program the higher your SD is the more inaccurate your average muzzle velocity will be for your ballistic program . Am I right or wrong , if I'm wrong what method should a person use to determine the best muzzle velocity number for the ballistic program?