Does good at close mean good at far?

[redneckmedic]

When doping a rifle to a certain load or in the case of rimfire a certain factory match lot, does a well performance load at 100yrds = the best choice for predictability at distance? All variables equal that is. I don't want to get into rounds that buck the wind or rounds that are only made for longer range. I am talking about load development. It seems that the standard is MOA at 100 yards (or MOA as a unit, Sub-MOA as a result)

I just wonder if going through all the pain stakes of finding the right variables for bullet type, weight, powder, charge, OAL, crimp tightness, barrel cleanliness, ect, ect, ect, ect, at 100 yards is worth all the time and pain when your over all goal might be 300, 600, or 1000+

 

[aclark]

Great question RNM. Not having any experience with load development yet, and wanting to get into some semi-serious reloading eventually, I will be watching this thread to see what comes of it.

rep'd

 

[IndyGunworks]

I dont think a good load at 100 yards would neccessarily be good at further yards... case in point.
say you have a load that shoots .5 moa at 100 yards with a 168 grain seirra matchking and a .75 moa groupd with a 175 grain SMK. the 175 will almost certainly give you more consistant results further down range because of retained velocity (wind deflection excluded from this example) the further you shoot, the more the 175 will triumph over the 168.

that said, if all things are the same 1 moa at 100 yards should still be 1 moa at 400 yards shooter and environmental conditions excluded and provided that you are within the limitations of that particular round/load

i can elaborate if need be but then we will be talking environmental conditions, ballistic coeffecients and a whole lot more stuff that wont really make my answer any different.

it is possible to have a round that doesnt full stabilize until further distances and gives you rather bad accuracy at closer distances but significantly better accuracy after a certain distance. the 408 cheytac comes to mind. while i have not experience with this round i have heard of people getting well over 1 moa inside of 300 yards, but 1/4 moa after. not that this is the norm, but its not completely unheard of.

 

[redneckmedic]

I dont think a good load at 100 yards would neccessarily be good at further yards...

So to make a long story short, if you are putting together a 500 yd round, you should only do load development at 500? Something seems so very against the grain about that idea.

 

[IndyGunworks]

the thing you are not going to see at 100 yards though is verticle stringing from your deviation of velocities otherwise known as standard deviation or SD. at 100 yards the rounds just dont have enough time to show this varience. once you start getting out there if you have a high SD or inconsistant velocities its quite possible to see a 1 moa group become 2 or 3 moa.

 

[redneckmedic]

the thing you are not going to see at 100 yards though is verticle stringing from your deviation of velocities otherwise known as standard deviation or SD.

Gotcha.. Please list every conceivable variable that would cause a difference in velocity, so I can be sure to eliminate them one at a time................

 

[kludge]

When doping a rifle to a certain load or in the case of rimfire a certain factory match lot, does a well performance load at 100yrds = the best choice for predictability at distance?

Not always.

Sometimes when working up a load with a particular combination of components you will have group that shoots fantastic groups at 100 yards, like 0.25" , but opens up at longer distances, like 3" at 300 yards, whereas a groups that shoots merely good groups at 100 yards, like 0.6", and great groups at 300 yards like 1.5".

Several variables are at play. At 100 yards it is very difficult to notice the effects of standard deviation and extreme spread of muzzle velocity. The ES will determine the vertical height of the group at long ranges. The higher the ES the more the vertical spread and the larger he group size. If fact ES can be THE determining factor at extreme ranges.

If you are getting low ES but bad groups, it's likely that barrel harmonics/bullet combination that are the culprit...

Another variable is the harmonic motion of the barrel. Each bullet weight, and even each bullet style can change the harmonics of the barrel. The barrel can have up and down and/or side to side motion as the bullet travels down the barrel. There is also a pressure wave running up and down the barrel at the speed of sound in steel. If you look at harmonic motion (sine wave) you will notice that at the peak and trough of the wave there is a moment when the wave is "motionless" or at least has "less motion" (change in amplitude as a function of time). If the bullet exits the barrel each time at the instant when the barrel is at the peak of its up or down or left or right (or a combination) movement it will exit when the barrel is "motionless" or nearly so. On the other hand if the bullet exits when the barrel is at the center of an up/down/left/right movement the muzzle is at its peak velocity and adding that up with the variations in muzzle velocity (and therefore "barrel time") you will a more scattered pattern on your target.

For tight groups at long range you need both low ES and be shooting a load that is compatible with your barrel.

If you're getting great groups at 100 yards but bad extreme spreads, you have found a bullet/velocity combination that your barrel likes (it only take a tiny variation +/-0.0083 degrees to make a 1 MOA group at 100 yards). However an inconsistent burn (high ES) will lead to vertical stringing at long range. Try a different powder that will burn more more consistently at that velocity in your chamber.

If you're getting low ES but the groups are not as good as you want, try changing things up, try more or less powder, different seating depths, a different bullet brand, or weight. Sometimes lowering the velocity 50fps can make a huge difference in group size, but I don't play with seating depth until I've found the bullet/primer/powder combination that my rifle likes. Some barrels love 62gr but hate a 69gr. Remember too that a powder at the extremes of pressure (i.e. near or beyond min and max loads) can behave erratically.

Also shooting 3-shot groups is not a tell-all of load accuracy. Anybody can flip three heads in a row. (probabiltiy = 13%) Flipping 7 heads in a row is probability of 0.8%.

Ladder tests and "OCW" test both have their place and can be effective ways to find THAT load for your rifle.

 

[42769vette]

your sd is never going to be perfect. the best ive ever done was 7 fps over a 5 shot group.

but anyways some bullets take awhile to calm down. some bullets are clam out of the barrel. the only way to find out is to test, test, test.

i can tell you on my comp 260 the load that shoots 1 inch @ 300 yds shoots .7 @ 100yds

 

[sloughfoot]

I will jump in here.

1. consistant charge weight.
2. consistant brass weight.
3. consistant bullet weight.
4. consistant neck tension.
5. match primers.

At 100 yards the bullet is traveling basically, horizontally. At distance, the bullet is arcing down into the target. For long range, consistant bullet speed is essential to keep this downward arc consistant.

100 yard shooting without a chronograph doesn't tell you much about how good a load is at 600 yards plus..

 

[42769vette]

another point on sd.

@ 1000yds 15fps means 6 inches or poi change. with my 260

 

[IndyGunworks]

I was going to do a chart to show what SD and ES can do to your groups but i think these two posts explain it WAY better than my chart would have.

Not always.

Sometimes when working up a load with a particular combination of components you will have group that shoots fantastic groups at 100 yards, like 0.25" , but opens up at longer distances, like 3" at 300 yards, whereas a groups that shoots merely good groups at 100 yards, like 0.6", and great groups at 300 yards like 1.5".

Several variables are at play. At 100 yards it is very difficult to notice the effects of standard deviation and extreme spread of muzzle velocity. The ES will determine the vertical height of the group at long ranges. The higher the ES the more the vertical spread and the larger he group size. If fact ES can be THE determining factor at extreme ranges.

If you are getting low ES but bad groups, it's likely that barrel harmonics/bullet combination that are the culprit...

Another variable is the harmonic motion of the barrel. Each bullet weight, and even each bullet style can change the harmonics of the barrel. The barrel can have up and down and/or side to side motion as the bullet travels down the barrel. There is also a pressure wave running up and down the barrel at the speed of sound in steel. If you look at harmonic motion (sine wave) you will notice that at the peak and trough of the wave there is a moment when the wave is "motionless" or at least has "less motion" (change in amplitude as a function of time). If the bullet exits the barrel each time at the instant when the barrel is at the peak of its up or down or left or right (or a combination) movement it will exit when the barrel is "motionless" or nearly so. On the other hand if the bullet exits when the barrel is at the center of an up/down/left/right movement the muzzle is at its peak velocity and adding that up with the variations in muzzle velocity (and therefore "barrel time") you will a more scattered pattern on your target.

For tight groups at long range you need both low ES and be shooting a load that is compatible with your barrel.

If you're getting great groups at 100 yards but bad extreme spreads, you have found a bullet/velocity combination that your barrel likes (it only take a tiny variation +/-0.0083 degrees) to make a 1 MOA group at 100 yards. However an inconsistent burn (high ES) will lead to vertical stringing at long range. Try a different powder that will burn more more consistently at that velocity in your chamber.

If you're getting low ES but the groups are not as good as you want, try changing things up, try more or less powder, different seating depths, a different bullet brand, or weight. Sometimes lowering the velocity 50fps can make a huge difference in group size, but I don't play with seating depth until I've found the bullet/primer/powder combination that my rifle likes. Some barrels love 62gr but hate a 69gr. Remember too that a powder at the extremes of pressure (i.e. near or beyond min and max loads) can behave erratically.

Also shooting 3-shot groups is not a tell-all of load accuracy. Anybody can flip three heads in a row. (probabiltiy = 13%) Flipping 7 heads in a row is probability of 0.8%.

Ladder tests and "OCW" test both have their place and can be effective ways to find THAT load for your rifle.

your sd is never going to be perfect. the best ive ever done was 7 fps over a 5 shot group.

but anyways some bullets take awhile to calm down. some bullets are clam out of the barrel. the only way to find out is to test, test, test.

i can tell you on my comp 260 the load that shoots 1 inch @ 300 yds shoots .7 @ 100yds

 

[kludge]

Indy, go ahead and do the chart. A picture is worth a thousand word.

 

[indyjoe]

100 yard group is enough to be a REAL good predictor, if Chrono data is also measured. That will tell you if there is variation that would cause it to open up at distance.

 

[Yeah]

Unless the objective of your shooting a rifle is to print the smallest possible 100 yard group, 100 yard groups will tell you very little. Chase low SD and maximum velocity with a reliable chronograph, known good bullet seated to the lands, and stable powder.

Most everything else is a matter of developing a technique that yields consistency.

 

[Robert Richardson]

Well there you go, reloading is "Rocket Science" wow!
Do you guys really talk like this?

 

[IndyGunworks]

Well there you go, reloading is "Rocket Science" wow!
Do you guys really talk like this?

what are you talking about? nothing we are saying is rocket science once you get a grasp on it all.

 

[42769vette]

actually i do talk like this all the time. unless im talking to nick it drives everyone nuts.

another note. pretty much the only time i shoot my loads at 100 anymore is if im paying alot more attention to my chrono than i am grouping

 

[Yeah]

Everyone's idea of what constitutes "rocket science" is different, usually correlated with their grasp of same.

 

[indyjoe]

Well there you go, reloading is "Rocket Science" wow!
Do you guys really talk like this?

As an Engineer, I would ask: Doesn't everyone?

By the way, it is actually External Ballistics, not Rocket Science, because there is no additional propulsion after the bullet leaves the barrel, so no rockets...

 

[Leadeye]

While I don't shoot at 300+ yards anymore I have had stability issues with bullets really open up groups at 150 that looked good at 100. Marlin 1894s do this in 44 mag with bulllets when they start getting heavier that 250 grains. I have not tried the Lee 300 RNF but would imagine this would have this problem in 44 mag. One of my planned retirement projects is to try this bullet in 444.