How to determine "best" load for long range shooting

[bgordon]

Just wondering how everybody utilizes group size and shape as part of determining the "best" load recipe specifically for ranges of 500 yards and beyond?

For me, at ranges of 300 yards and closer it is a no brainer. I try to do load development on relatively still evenings so that any wind induced stringing is minimized.
At 500 yards and beyond, it seems like no matter what I do there is some horizontal stringing. My best method is to do 5 shots as quickly as can be done accurately. If I try to read the conditions on each shot and space the shots far enough apart to keep the barrel cool, there is a definite amount of horizontal grouping to the shots.
The horizontal spread happens most of the time, unless I just happen to get good (or lucky) at reading the conditions. For this reason I normally use the accumulated vertical dispersion of 2 or 3 five shot groups to determine load potential at 500 yards and beyond.

 

[DANTEC]

what to you need

tight group

or

a good idea of your rifle accuracy potential

first I start to check only the elevation of the group , on a good rifle with barrel/barrel fitting/action/stock OK , the vertical spread is near to equal the horizontal spread so if your elevation is 1 inch your group size potential is 1 x 1.414 = 1.414 inch even if with wind your horizontal spread is 4 inch .

the vertical spread is make ( principal )by

Variation of BC ( can be check by ogive lenght checking on bullets )
SD of velocity ( good load with minimum SD can be test at muzzle velocity )defect done by :
Case capacity ( direct effect on velocity )
primer setting
flash hole deburing
load density ( use load near max load density to avoid powder moove in the case with coorect burning rate to avoid overpressure)

if you want to reach the potential accuracy you need to learn to shoot

fast : you get the same wind when wind is good

slow : you wait each time the wind return to initial condition of your first shot

compensate : you read the wind before to shoot ( fast ) and you modify your scope set up or use your mil dot multi line reticule to compensate the effect of the wind .

Good shooting and enjoy shooting in the wind

DAN TEC

 

[Timberwolfhd]

Just wondering how everybody utilizes group size and shape as part of determining the "best" load recipe specifically for ranges of 500 yards and beyond?

For me, at ranges of 300 yards and closer it is a no brainer. I try to do load development on relatively still evenings so that any wind induced stringing is minimized.
At 500 yards and beyond, it seems like no matter what I do there is some horizontal stringing. My best method is to do 5 shots as quickly as can be done accurately. If I try to read the conditions on each shot and space the shots far enough apart to keep the barrel cool, there is a definite amount of horizontal grouping to the shots.
The horizontal spread happens most of the time, unless I just happen to get good (or lucky) at reading the conditions. For this reason I normally use the accumulated vertical dispersion of 2 or 3 five shot groups to determine load potential at 500 yards and beyond.

gun)I shoot F-Class competition. You need a good chronograph! You then fire your different loads in 10 shot groups, then use the load that has the LOWEST SD (standard deviation). The "best" loads are the ones that have an SD of 20 - 25 fps or less. The reason is this: A deviation of 50 fps can make your shot have a vertical dispersion of 7 inches or more at 1000 yds, which will mean a complete miss or a wounded animal for you to chase.
If you get more than 1 load with an SD of below 20 fps, fire them at 100 yds to see which one is more accurate. This tells you which load your gun "likes" better.
As far as the horizontal spread goes, it takes practice at reading the wind and compensating for it, either by scope adjustment or hold. There is no magic "formula" for learning wind reading, the more you do it, the better you get at it.
I started in F-Class by reading a couple (then a 3rd) books that I highly recommend: "Reading the Wind and Coaching Techniques" by M/Sgt James Owens, "Prone and Long-Range Rifle Shooting" by Nancy Tompkins, and "Applied Ballistics for Long Range Shooting" by Bryan Litz.

 

[bigbuck]

gun)I shoot F-Class competition. You need a good chronograph! You then fire your different loads in 10 shot groups, then use the load that has the LOWEST SD (standard deviation). The "best" loads are the ones that have an SD of 20 - 25 fps or less. The reason is this: A deviation of 50 fps can make your shot have a vertical dispersion of 7 inches or more at 1000 yds, which will mean a complete miss or a wounded animal for you to chase.
If you get more than 1 load with an SD of below 20 fps, fire them at 100 yds to see which one is more accurate. This tells you which load your gun "likes" better.
As far as the horizontal spread goes, it takes practice at reading the wind and compensating for it, either by scope adjustment or hold. There is no magic "formula" for learning wind reading, the more you do it, the better you get at it.
I started in F-Class by reading a couple (then a 3rd) books that I highly recommend: "Reading the Wind and Coaching Techniques" by M/Sgt James Owens, "Prone and Long-Range Rifle Shooting" by Nancy Tompkins, and "Applied Ballistics for Long Range Shooting" by Bryan Litz.

+1 The only thing I can add is that I've heard that if you have an SD in the single digits you have a good long range load (but ) you should go out and shoot it to make sure

Bigbuck.

 

[jwp475]

Once I have settled on a load and have verified my drop, I never shoot more than 3 shots. I do not think that I would ever shoot more than 3 at an animal and that is all that I am after, since I am a long range hunter not a competitor.
I like to set up a target and fire 1 round come back a few days latter and shot 1 more round a few days latter and shoot 1 round. This give me a good indication of what to expect from a cold barrel, which is how it will be in the hunting field.
Last year just before going on my Elk hunt I fired 3 rounds over 7 days and had about a 2" group at 600 yards with my 338 Lapua. I called that good to go

 

[bigbuck]

Once I have settled on a load and have verified my drop, I never shoot more than 3 shots. I do not think that I would ever shoot more than 3 at an animal and that is all that I am after, since I am a long range hunter not a competitor.
I like to set up a target and fire 1 round come back a few days latter and shot 1 more round a few days latter and shoot 1 round. This give me a good indication of what to expect from a cold barrel, which is how it will be in the hunting field.
Last year just before going on my Elk hunt I fired 3 rounds over 7 days and had about a 2" group at 600 yards with my 338 Lapua. I called that good to go

jwp475,

2'' cold bore group @ 600 yrds I'm going to try this can you tell me what kind of group you would consider bad doing it this way?Example would you say from 2'' to 4'' anything bigger then that would not be good.

Thanks
Bigbuck

 

[Mikecr]

+1 JWP475
It's consistant -cold barrel -single shots that matter here.

I also have to say that I don't get the assumption that horizonatal EQUALS verticle.
They are two seperate events, that can be independent of each other.
For example, you could have vertical w/little horizontal due to BC variance, ES, and barrel tune/release.
Or, you could have horizontal w/little vertical for exactly the same reasons, but under different shooting conditions(like temp, wind & distance).

 

[Timberwolfhd]

Once I have settled on a load and have verified my drop, I never shoot more than 3 shots. I do not think that I would ever shoot more than 3 at an animal and that is all that I am after, since I am a long range hunter not a competitor.
I like to set up a target and fire 1 round come back a few days latter and shot 1 more round a few days latter and shoot 1 round. This give me a good indication of what to expect from a cold barrel, which is how it will be in the hunting field.
Last year just before going on my Elk hunt I fired 3 rounds over 7 days and had about a 2" group at 600 yards with my 338 Lapua. I called that good to go

gun)When I'm working up loads for hunting, I agree, however, you start by saying "once I have settled on a load", what I described is the way to settle on a load.

 

[LouBoyd]

gun)When I'm working up loads for hunting, I agree, however, you start by saying "once I have settled on a load", what I described is the way to settle on a load.

I use Quickload and Quicktarget computer simulations to help select appropriate loads. The programs do not tell how accurate a given load will be, but they do tell how sensitive the load should be to muzzle velocity variations and to wind deflection if the rifle is perfect. It also predicts muzzle velocities, case fills, muzzle pressure, and bore time. It can even predict velocity variations vs such things as bullet weight variation, charge variation, case volume variation and bore friction variation. All of that can help in estimating which loads may be more accurate but there are enough factors which aren't even addressed to prevent it from actually predicting group sizes. It can tell you a group size that a perfect rifle isn't likely to beat.

The uncertainties of wind estimation increase faster than linearly with increased range both because bullets slow down with distance and the wind is less likely to be the same as at the firing position. At long enough ranges the firing position isn't even the place most sensitive to wind. Vertical stringing resulting from velocity variations increases with more than the square of the distance. It is exactly proportional to the square of the time of flight, but bullets slow down with distance. It helps to have an idea of what group sizes are realistic to achieve before beating yourself to death trying to find find constantly small groups which the range conditions simply won't allow.

Use a good chronograph and wind flags or meters when trying to find good loads. Do most of the testing at the actual distances you expect to shoot. You won't sort out what errors are caused by the rifle, the ammo, and the atmosphere without that. Maybe not with them either but you'll have a better chance.