ES inverse of accuracy

[Woolsocks]

Took my first swipe at reloading. Building up a load for a 28 nos.

Unfortunately, I seem to have a habit of collecting data without having the foggiest idea what it means. In this case, I find it odd that my ES seems to go up as my accuracy increases. Seems like the opposite would be true?

Two Caveats:
I’m using a Labradar. I had to use the radar trigger rather than the audio trigger, so I’m not sure where downrange the projectile’s velocity is being read. With the Labradar sitting on the bench with my rifle, it’s conceivable that the recoil slightly changed the position of the chrono, so perhaps it’s not catching it at a uniform location.
This is a pretty small data pool. The load range for this recipie is 77-81gr. I’ve only tested 77-79.

Here’s the data. It’s a 28nos. Using 160gr accubonds, H1000, once-fired nosler brass and CCI 200 primers.

Using 77gr H1000- group size is 1.9MOA, Avg Velocity is 3073. ES is 17.
Using 78gr H1000 - group size is 1.4MOA, Avg Velocity is 3138, ES is 40
Using 79gr H1000 - group size is 0.87MOA, Avg Velocity is 3179, ES is 61

Why is my ES going up with velocity, and inverse of accuracy? Any chance the ES will even out as increase the powder charge?

 

[Rio Precision Gunworks]

You're attempting correlate things that are independent of one another.

Inside a few hundred yards, velocity is high enough that large variations don't affect group size. Once you get past a few hundred yards, it does matter. So what you'll see if you stretch out those charge weights to longer distance, the larger ES will exhibit larger group dispersion.

And this is assuming that your above posted data is actually representative of your ammo and not just a product of small sample size variance. And it's a magnum rifle. Generally speaking, people universally perform worse with large magnums due to recoil management. So you'd also have to be very sure you're not the cause of some of the larger group sizes.

 

[Rio Precision Gunworks]

Also, what's your SD and how many shots for those charge weights? That is going to paint a much better picture than ES.

 

[Woolsocks]

Also, what's your SD and how many shots for those charge weights? That is going to paint a much better picture than ES.

6.94, 14.78 and 23.21 respectively, if my math is correct. 5 shots per charge weight.

 

[Rio Precision Gunworks]

With small sample sizes such as 5 shots, the best you can do is eliminate charges. 78 and 79gr aren't looking too good. The downside is, while you can eliminate with small samples, you can't use it to choose a charge weight or say that a charge weight is good.

For example, if a batch of ammo has a 15sd, and you shot 200 five round strings, around 13% of the time, you'd have an SD of 10 or lower. That's better than 1/10, which makes it extremely possible to get one of these shot strings.

So, the best you can do at the moment is make more ammo with 77gr and see if the SD holds up.


The TLDR version: you don't have enough data to say with any confidence that you're getting better precision with higher ES, as you have no idea if that low ES is a proper representation of the ammo.

 

[RegionRat]

Agree with Rio Precision.

You can abandon things that look bad early, but the opposite is also true in that you can't call anything good with small samples.

When you see bad groups with small samples, shooting more won't make them better. But, when you think you have a good one, the only way to know is to shoot more.

Without seeing the actual data... when you see an ES/SD ratio that is near 4 with smaller samples and with more samples the ratio approaches 5 to 6, then things filling out to a normal distribution statistically speaking. When those ratios are not roughly 4 to 6, then the fat lady hasn't sung yet, and when they are already going badly, don't expect them to get better with more samples.

You end up needing a solid SD near 5 to stay inside an ES of 30 over a long string. A short term SD of 7.5 might stay under 30 ES, but not for very long.

If your vertical stays good at distance over long strings, then by definition the velocity stats are good. If your velocity stats are good but your groups suck, then those velocity stats are cold comfort.

 

[Woolsocks]

Agree with Rio Precision.

You can abandon things that look bad early, but the opposite is also true in that you can't call anything good with small samples.

When you see bad groups with small samples, shooting more won't make them better. But, when you think you have a good one, the only way to know is to shoot more.

Without seeing the actual data... when you see an ES/SD ratio that is near 4 with smaller samples and with more samples the ratio approaches 5 to 6, then things filling out to a normal distribution statistically speaking. When those ratios are not roughly 4 to 6, then the fat lady hasn't sung yet, and when they are already going badly, don't expect them to get better with more samples.

You end up needing a solid SD near 5 to stay inside an ES of 30 over a long string. A short term SD of 7.5 might stay under 30 ES, but not for very long.

If your vertical stays good at distance over long strings, then by definition the velocity stats are good. If your velocity stats are good but your groups suck, then those velocity stats are cold comfort.

Interesting. Well, as of now it seems I haven’t found the optimal load (77 and 78gr are inaccurate, 79gr has too large ES). I suppose the thing to do is to continue increasing the charge toward the upper end of 81gr. If that doesn’t work, try another powder.

 

[Doom]

@Woolsocks , we seem to have a never-ending discussion on ES and SD, small sample sizes and and all it entails. The above comments are correct and helpful. Let me add a couple of points:

1. No matter how many shots are fired the ES is made up of only two. In reality, ES has no statistical meaning.
2. 5 to 10 shots will give you a good idea of your average velocity.
3. It takes at least 20 shots to begin to have confidence in your standard deviation.
4. The LabRadar estimates Vo at the muzzle based on where it picks up the bullet.
5. If shooting groups at 100 yds you cannot correlate group size and velocity. A 100fps spread would only equate to a 0.3" spread or about one bullet diameter.
6. The target tells you how the rifle system (including shooter, cartridge, rifle) is performing. The statistics tell you information on how the cartridge is performing. The target trumps the chronograph.

 

[Woolsocks]

@Woolsocks , we seem to have a never-ending discussion on ES and SD, small sample sizes and and all it entails. The above comments are correct and helpful. Let me add a couple of points:

1. No matter how many shots are fired the ES is made up of only two. In reality, ES has no statistical meaning.
2. 5 to 10 shots will give you a good idea of your average velocity.
3. It takes at least 20 shots to begin to have confidence in your standard deviation.
4. The LabRadar estimates Vo at the muzzle based on where it picks up the bullet.
5. If shooting groups at 100 yds you cannot correlate group size and velocity. A 100fps spread would only equate to a 0.3" spread or about one bullet diameter.
6. The target tells you how the rifle system (including shooter, cartridge, rifle) is performing. The statistics tell you information on how the cartridge is performing. The target trumps the chronograph.

Thanks. I think no 4 isn’t correct since I was using the Doppler trigger (the internal trigger wasn’t working for some reason). Hence wondering if these readings can be trusted. If it’s catching one shot at 10 yards, then the next at 40, that would lead to a large spread of velocity readings even if the load is fine.

 

[spife7980]

Labradar is radar, thus it collects bunches of radar ping returns over time and distances and calculates the curve making a best fit line and by extrapolation that line can trace it back to what it would have been at the muzzle.
It’s collecting every shot at 10 and 40 yard. And 2, 8, 15, 23, 35, 48, 56,68, 77, 83 etc

 

[RegionRat]

When you have time, pull the data from the card in your LR and open the CSV folders. You will find the summary file will open if you have a spreadsheet program like Excel or similar. Then, open the detailed files which will show you how those individual shots were processed.

You will see that what the LR is doing is picking up shots at some distance from the antenna, but then they extrapolate back to calculate the velocity at the muzzle.

Like @spife7980 is saying, the shots are all captured at slightly different distances from the antenna, but the extrapolation is back to the antenna which is assumed to be less than half a meter from the muzzle.

Those downrange distances are from the LR antenna and the unit can only capture the reflection when the bullet breaks into the beam and no sooner. Then there is some noise filtering to get to the first data points which means even a little farther before they show data points. The estimated distance to the first reflection is then a calculated value and the extrapolation using the whole data set can be done.

Hope that makes some sense as it is difficult to put into words and I am a horrible writer. It is easier to explain in front of a white board, but without turning this into a class on RF and radar, that's what you will get for free. YMMV

 

[.505gibbs]

Took my first swipe at reloading. Building up a load for a 28 nos.

Unfortunately, I seem to have a habit of collecting data without having the foggiest idea what it means. In this case, I find it odd that my ES seems to go up as my accuracy increases. Seems like the opposite would be true?

Two Caveats:
I’m using a Labradar. I had to use the radar trigger rather than the audio trigger, so I’m not sure where downrange the projectile’s velocity is being read. With the Labradar sitting on the bench with my rifle, it’s conceivable that the recoil slightly changed the position of the chrono, so perhaps it’s not catching it at a uniform location.
This is a pretty small data pool. The load range for this recipie is 77-81gr. I’ve only tested 77-79.

Here’s the data. It’s a 28nos. Using 160gr accubonds, H1000, once-fired nosler brass and CCI 200 primers.

Using 77gr H1000- group size is 1.9MOA, Avg Velocity is 3073. ES is 17.
Using 78gr H1000 - group size is 1.4MOA, Avg Velocity is 3138, ES is 40
Using 79gr H1000 - group size is 0.87MOA, Avg Velocity is 3179, ES is 61

Why is my ES going up with velocity, and inverse of accuracy? Any chance the ES will even out as increase the powder charge?

The CCI 200 primers probably aren’t doing you any favours. They are a fairly mild large rifle primer.

 

[Rocketmandb]

Interesting. Well, as of now it seems I haven’t found the optimal load (77 and 78gr are inaccurate, 79gr has too large ES). I suppose the thing to do is to continue increasing the charge toward the upper end of 81gr. If that doesn’t work, try another powder.

My load development method:

1) Form brass if not already done

If I don't know the upper limits of the case/bullet/powder combo:

2) Shoot a couple ladders to find the edge of pressure
3) Decide on a safe velocity range that I want to test in
4) Shoot 5 shot strings at either .2 or .3 grain increments
5) Eliminate the bad ones and choose a couple to validate against
6) Load 20 rounds against those charge weights and see what the SDs come out at
7) If good, pick one and play with seating depth to bring in precision.

In short, powder charge for SDs, seating depth for group size.

 

[MarkyMark007]

Why is my ES going up with velocity, and inverse of accuracy? Any chance the ES will even out as increase the powder charge?

because you have hunting rifle, with hunting cartridge, with hunting bullet, with hunting powder, with small sample size, with bad precision.

that's why your data are not worth much.

 

[Rust]

If you're using Accubonds you've probably got a hunting rifle and to be honest 3/4 moa is pretty good for an off the rack rifle. If it's a heavy target rifle you wouldn't be using Accubonds.

If you aren't getting the best accuracy and ES simultaneously I'd say it's time to try a different powder and/or primer. Only change one thing at a time. Most rifles I've had, the competition rifles too, at the same target velocity have differing accuracy and ES/SD numbers with different powders. Primers can have the same effect. When you experiment only change one thing at a time. My favorite competition rifle has a node a 2940 fps ten feet off the screens and only one powder gave the tightest accuracy and ES/SD. Others anywhere from close to no way.

I don't get all excited chasing numbers, not going to burn up a 1,200 round match barrel going for a "statistically relevant" SD. If I get a ten round ES of 7 during load development the SDs are going to be low. I figure it's fine and go to 1,000. If it holds the bull and a good waterline at 1,000 I'm a happy camper. Well, except at the Ben Avery when the wind is up and the flags lie like a rug. Been a few years since I've been out there though.

Hunting rifles are a different story. I have a couple that took effort to get close to 1 moa, and a couple that hit under 1/2 moa no problem. Of course most of those have good match grade barrel replacements. But the above still holds true, a rifle likes what it likes and there isn't always a one thing fits all solution.

 

[Rio Precision Gunworks]

because you have hunting rifle, with hunting cartridge, with hunting bullet, with hunting powder, with small sample size, with bad precision.

that's why your data are not worth much.

Ignore all of this. You can make plenty good ammo in 28 nosler with Accubonds. Obviously it won't be benchrest ammo. But you can easily get SDs in the upper single or low double digit (actual SD).

Just posting to make sure no one listens to this dude.....ever.

 

[Haney]

Just posting to make sure no one listens to this dude.....ever.

Bullshit, you are "Just" posting because you like to think of yourself as an expert and have a big mouth . Give us a break .

 

[supercorndogs]

Bullshit, you are "Just" posting because you like to think of yourself as an expert and have a big mouth . Give us a break .

Especially when compared to you and markymark, he is.

 

[Woolsocks]

If you're using Accubonds you've probably got a hunting rifle and to be honest 3/4 moa is pretty good for an off the rack rifle. If it's a heavy target rifle you wouldn't be using Accubonds.

If you aren't getting the best accuracy and ES simultaneously I'd say it's time to try a different powder and/or primer. Only change one thing at a time. Most rifles I've had, the competition rifles too, at the same target velocity have differing accuracy and ES/SD numbers with different powders. Primers can have the same effect. When you experiment only change one thing at a time. My favorite competition rifle has a node a 2940 fps ten feet off the screens and only one powder gave the tightest accuracy and ES/SD. Others anywhere from close to no way.

I don't get all excited chasing numbers, not going to burn up a 1,200 round match barrel going for a "statistically relevant" SD. If I get a ten round ES of 7 during load development the SDs are going to be low. I figure it's fine and go to 1,000. If it holds the bull and a good waterline at 1,000 I'm a happy camper. Well, except at the Ben Avery when the wind is up and the flags lie like a rug. Been a few years since I've been out there though.

Hunting rifles are a different story. I have a couple that took effort to get close to 1 moa, and a couple that hit under 1/2 moa no problem. Of course most of those have good match grade barrel replacements. But the above still holds true, a rifle likes what it likes and there isn't always a one thing fits all solution.

Point taken. It does seem to have a nice hand-lapped barrel on there. Fierce sent it with target showing 0.3 MOA for their factory test. I’m getting sub- MOA with their ammo and with my first attempt at handholds. It’s accurate enough that my shooting ability probably the limiting factor. I think accuracy is going to be the easy part, though it seems to be terribly inaccurate with loads at the lower end of the ladder.

Velocity seems to be the difficulty. It’s giving velocity spreads of 60 or so with both fierce’s ammo and mine. I’m using an RCBS 304 scale and weighing each charge, so I assume it’s not user error. I’m hoping magnum primers do something for me. If they don’t, maybe switching from H1000 to Retumbo will do something.

Of course, I was hoping for “according to the data X, the problem is obviously Y”, or a dissertation on the exact things that cause ES. Sounds like the answer is “try stuff and see what works”. No shortcuts

 

[Rocketmandb]

I’m hoping magnum primers do something for me.

This might come off as condescending, but that is not the purpose, so my apologies if you take it that way.

Don't hope, think. What will magnum primers do to the equation? They have more explosive material inside, so they ignite more quickly and thus impart more energy to the powder in the case more quickly. This will speed up combustion, which will in turn build more pressure more quickly. Will that in itself do anything to your ES/SD? In most cases for your size case, no. In extreme cold, perhaps. I don't get that you're testing in extreme cold.

The key element in getting consistent velocity is getting a consistent pressure profile. Things that affect the pressure profile:

Powder Distribution in the Case

If you have a case that's not at optimum fill (e.g. there is extra "vacancy" in the case after charging), then the powder can be spread differently throughout the case when you load it. If all the powder is at the front of case and limited is at the back, that will give you a slower pressure build than the reverse where more powder is burning sooner in the process. The optimum powder/load is the one that will:

1) Fill the case as much as possible without getting compressed loads (breaking powder changes its burn rate)
2) Burn all the powder while the projectile is in the barrel
3) Not go over pressure

The goal should be to have even distribution shot to shot.


Effective Neck Tension

Effective neck tension is the combination of all forces that hopelessly conspire to keep your bullet seated in the case (in other words, things that work against the pressure building). These include:

1) Brass interference fit (what many call neck tension) - the higher the interference, the more the brass will tend to hold the bullet in place.
2) Brass elasticity - the more elastic, the more force it will impart from the neck to the bullet after it is pushed out during seating.
3) Coefficient of friction between the neck wall and the bullet - lubed bullets, lubed necks.
4) Area of the neck wall that is in contact with the bullet - if you aren't consistently sizing the neck to the same point case to case.

The above four things combine to create the overall friction holding the bullet in place - the Effective Neck Tension. If that isn't consistent, you get varying pressure profiles shot to shot.


Other Things Impacting the Pressure Profile (some minor, some less so)

Seating Depth: Seating close to the lands (or jammed into them) will yield a different pressure profile than, for example, seated 150 thousandths off. If you are not seating consistently, this will have an impact - easy to measure.

Primer Pocket Uniforming and (Related) Primer Seating: Different depths change primer ignition pattern and thus burn - minor, but they all add up.

Flash Hole Deburring: If a piece of metal is interfering with the flash hole on one case and not on another, there will be different ignition patterns between the two, which will impact burn rate, which will impact the pressure profile.

Quality and Material of Bullets: If a bullet is not consistent in how it reacts after reaching the lands, you can get a change in pressure profiles.

If they don’t, maybe switching from H1000 to Retumbo will do something.

Retumbo is slightly slower than H1000, which will give you slightly more fill (good), but both are high-quality consistent powders in the same burn rate regime. But switching powders before you get a good handle on your reloading process is just shooting blind.

What I'd do first:

- Try another bullet? Why so light? Why Nosler? Get some Bergers! (180 hybrids are available)
- Evaluate every step of your loading process - are you being consistent all along the way?
- You picked essentially three random charge weights and started basing conclusions off of those. Pick something in the middle, go up at like .3gr increments, 5-shots a piece. Eliminate really bad ES/SD, pick a couple/few of the better ones and test them with 20+ shots each.
- Look less at ES and more at SD - what is causing the high numbers in a group? Were the values scattered across the velocity range, or were like 4 shots really close together and one was way out that caused the higher value? Many times (certainly not always) that is user error somewhere in the reloading process.
- Focus less on group size for now. Get a good-performing ES/SD that has at least a decent group size, then tune the group size in with seating depth.

EDIT: What is your seating depth? And just to make sure, you aren't crimping, are you?

 

[Woolsocks]

This might come off as condescending, but that is not the purpose, so my apologies if you take it that way.

Don't hope, think. What will magnum primers do to the equation? They have more explosive material inside, so they ignite more quickly and thus impart more energy to the powder in the case more quickly. This will speed up combustion, which will in turn build more pressure more quickly. Will that in itself do anything to your ES/SD? In most cases for your size case, no. In extreme cold, perhaps. I don't get that you're testing in extreme cold.

The key element in getting consistent velocity is getting a consistent pressure profile. Things that affect the pressure profile:

Powder Distribution in the Case

If you have a case that's not at optimum fill (e.g. there is extra "vacancy" in the case after charging), then the powder can be spread differently throughout the case when you load it. If all the powder is at the front of case and limited is at the back, that will give you a slower pressure build than the reverse where more powder is burning sooner in the process. The optimum powder/load is the one that will:

1) Fill the case as much as possible without getting compressed loads (breaking powder changes its burn rate)
2) Burn all the powder while the projectile is in the barrel
3) Not go over pressure

The goal should be to have even distribution shot to shot.


Effective Neck Tension

Effective neck tension is the combination of all forces that hopelessly conspire to keep your bullet seated in the case (in other words, things that work against the pressure building). These include:

1) Brass interference fit (what many call neck tension) - the higher the interference, the more the brass will tend to hold the bullet in place.
2) Brass elasticity - the more elastic, the more force it will impart from the neck to the bullet after it is pushed out during seating.
3) Coefficient of friction between the neck wall and the bullet - lubed bullets, lubed necks.
4) Area of the neck wall that is in contact with the bullet - if you aren't consistently sizing the neck to the same point case to case.

The above four things combine to create the overall friction holding the bullet in place - the Effective Neck Tension. If that isn't consistent, you get varying pressure profiles shot to shot.


Other Things Impacting the Pressure Profile (some minor, some less so)

Seating Depth: Seating close to the lands (or jammed into them) will yield a different pressure profile than, for example, seated 150 thousandths off. If you are not seating consistently, this will have an impact - easy to measure.

Primer Pocket Uniforming and (Related) Primer Seating: Different depths change primer ignition pattern and thus burn - minor, but they all add up.

Flash Hole Deburring: If a piece of metal is interfering with the flash hole on one case and not on another, there will be different ignition patterns between the two, which will impact burn rate, which will impact the pressure profile.

Quality and Material of Bullets: If a bullet is not consistent in how it reacts after reaching the lands, you can get a change in pressure profiles.



Retumbo is slightly slower than H1000, which will give you slightly more fill (good), but both are high-quality consistent powders in the same burn rate regime. But switching powders before you get a good handle on your reloading process is just shooting blind.

What I'd do first:

- Try another bullet? Why so light? Why Nosler? Get some Bergers! (180 hybrids are available)
- Evaluate every step of your loading process - are you being consistent all along the way?
- You picked essentially three random charge weights and started basing conclusions off of those. Pick something in the middle, go up at like .3gr increments, 5-shots a piece. Eliminate really bad ES/SD, pick a couple/few of the better ones and test them with 20+ shots each.
- Look less at ES and more at SD - what is causing the high numbers in a group? Were the values scattered across the velocity range, or were like 4 shots really close together and one was way out that caused the higher value? Many times (certainly not always) that is user error somewhere in the reloading process.
- Focus less on group size for now. Get a good-performing ES/SD that has at least a decent group size, then tune the group size in with seating depth.

EDIT: What is your seating depth? And just to make sure, you aren't crimping, are you?

Thanks. Not condescending at all.

What’s nagging me is the perfect relationship between my powder charge and ES/SD (they increase together). My statistics-oriented brain thinks that has to mean something…

Other stuff..
1. Bullets: is there any reason a heavier bullet would give better odds of a lower ES/SD? The factory ammo that shot .3moa was 160accubonds, so I thought that would be one variable I wouldn’t need to worry about to start with. With that said, that factory ammo also had 60fps ES
2. Primers. Wouldn’t an undersized primer cause inconsistent ignition? Nosler load data assumes WRLM primers, and most people seem to use them for 28nos, now that I’m asking around.
3. Seating depth. I’m shooting 30 thou off the lands. Not crimping.
4. Neck tension. Is there a way to know if it’s correct? I’m using a .314 bushing and the neck of a loaded round is .317. If anything a little tight, but it seats fine.

Not completely ruling out user error, but I kind of obsessed over those loads and triple-checked everything. The consistency of the lower charge weights also indicates that the process is working, just not the load.

The only odd thing I found was the inconsistency of the nosler brass. Case length after resizing varied from 10 thou under to 3 thou over. Can’t trim short cases longer, so I used em’. Again, if that was the problem, why were the lower charge weights consistent, and the hotter rounds not?

 

[308pirate]

I seem to have a habit of collecting data without having the foggiest idea what it means

That's about 95% of reloaders.

 

[straightshooter1]

This might come off as condescending, but that is not the purpose, so my apologies if you take it that way.

Don't hope, think. What will magnum primers do to the equation? They have more explosive material inside, so they ignite more quickly and thus impart more energy to the powder in the case more quickly. This will speed up combustion, which will in turn build more pressure more quickly. Will that in itself do anything to your ES/SD? In most cases for your size case, no. In extreme cold, perhaps. I don't get that you're testing in extreme cold.

The key element in getting consistent velocity is getting a consistent pressure profile. Things that affect the pressure profile:

Powder Distribution in the Case

If you have a case that's not at optimum fill (e.g. there is extra "vacancy" in the case after charging), then the powder can be spread differently throughout the case when you load it. If all the powder is at the front of case and limited is at the back, that will give you a slower pressure build than the reverse where more powder is burning sooner in the process. The optimum powder/load is the one that will:

1) Fill the case as much as possible without getting compressed loads (breaking powder changes its burn rate)
2) Burn all the powder while the projectile is in the barrel
3) Not go over pressure

The goal should be to have even distribution shot to shot.


Effective Neck Tension

Effective neck tension is the combination of all forces that hopelessly conspire to keep your bullet seated in the case (in other words, things that work against the pressure building). These include:

1) Brass interference fit (what many call neck tension) - the higher the interference, the more the brass will tend to hold the bullet in place.
2) Brass elasticity - the more elastic, the more force it will impart from the neck to the bullet after it is pushed out during seating.
3) Coefficient of friction between the neck wall and the bullet - lubed bullets, lubed necks.
4) Area of the neck wall that is in contact with the bullet - if you aren't consistently sizing the neck to the same point case to case.

The above four things combine to create the overall friction holding the bullet in place - the Effective Neck Tension. If that isn't consistent, you get varying pressure profiles shot to shot.


Other Things Impacting the Pressure Profile (some minor, some less so)

Seating Depth: Seating close to the lands (or jammed into them) will yield a different pressure profile than, for example, seated 150 thousandths off. If you are not seating consistently, this will have an impact - easy to measure.

Primer Pocket Uniforming and (Related) Primer Seating: Different depths change primer ignition pattern and thus burn - minor, but they all add up.

Flash Hole Deburring: If a piece of metal is interfering with the flash hole on one case and not on another, there will be different ignition patterns between the two, which will impact burn rate, which will impact the pressure profile.

Quality and Material of Bullets: If a bullet is not consistent in how it reacts after reaching the lands, you can get a change in pressure profiles.



Retumbo is slightly slower than H1000, which will give you slightly more fill (good), but both are high-quality consistent powders in the same burn rate regime. But switching powders before you get a good handle on your reloading process is just shooting blind.

What I'd do first:

- Try another bullet? Why so light? Why Nosler? Get some Bergers! (180 hybrids are available)
- Evaluate every step of your loading process - are you being consistent all along the way?
- You picked essentially three random charge weights and started basing conclusions off of those. Pick something in the middle, go up at like .3gr increments, 5-shots a piece. Eliminate really bad ES/SD, pick a couple/few of the better ones and test them with 20+ shots each.
- Look less at ES and more at SD - what is causing the high numbers in a group? Were the values scattered across the velocity range, or were like 4 shots really close together and one was way out that caused the higher value? Many times (certainly not always) that is user error somewhere in the reloading process.
- Focus less on group size for now. Get a good-performing ES/SD that has at least a decent group size, then tune the group size in with seating depth.

EDIT: What is your seating depth? And just to make sure, you aren't crimping, are you?

Excellent post, IMHO.

In terms of velocity, I really focus on SD's to tell me how well I'm doing with my reloading. In terms of what I get on paper, Mean Radius tells me how well everything is perform together (shooter, gun and ammo). ES doesn't say much where I can have a single POI far from a group the group 9 or 19 tells me more than that one errant POI. Though, I'd sure want to know what caused that "flyer"; more often than not, it's a shooter's error.

 

[Rocketmandb]

Thanks. Not condescending at all.

What’s nagging me is the perfect relationship between my powder charge and ES/SD (they increase together). My statistics-oriented brain thinks that has to mean something…

It doesn't - just an unrelated correlation.

Other stuff..
1. Bullets: is there any reason a heavier bullet would give better odds of a lower ES/SD? The factory ammo that shot .3moa was 160accubonds, so I thought that would be one variable I wouldn’t need to worry about to start with. With that said, that factory ammo also had 60fps ES\

A heavier bullet won't necessarily give a better ES/SD, but you lose velocity as your bullet travels - you don't lose weight Really, though, it comes down to right-sizing the bullet for the case - it also comes down to getting the best bullet you can. Berger > Nosler.

2. Primers. Wouldn’t an undersized primer cause inconsistent ignition? Nosler load data assumes WRLM primers, and most people seem to use them for 28nos, now that I’m asking around.

Yes, an undersized primer would. But is a standard LR primer undersized for that case? At certain temps, yes. At most temps you'll be shooting at, no. I use BR2s in my 300 PRC and have since the beginning. I tested 215M (magnum) vs. BR2s and found the BR2s to be slightly better for SDs.

3. Seating depth. I’m shooting 30 thou off the lands. Not crimping.

Not a bad place to play until you get your process down.

4. Neck tension. Is there a way to know if it’s correct? I’m using a .314 bushing and the neck of a loaded round is .317. If anything a little tight, but it seats fine.

You're at .003 then. Should be okay, but you might want to play a little bit there as you move forward.

The only odd thing I found was the inconsistency of the nosler brass. Case length after resizing varied from 10 thou under to 3 thou over. Can’t trim short cases longer, so I used em’. Again, if that was the problem, why were the lower charge weights consistent, and the hotter rounds not?

Yeah, Nosler is not so great. You can get ADG and Peterson for 28 Nosler, I believe. Might want to try one of those.

 

[quietmike]

Especially when compared to you and markymark, he is.

@Haney why would you come to an obviously conservative forum and spout your lefty BS?
Wouldn't you be equally upset if a priest showed up at your NAMBLA meetings?