First of all, forget about the chrono. Load develop for accuracy, then use your chrono for your speed. The magneetospeed will absolutely effect your group size and POI which has been confirmed hundreds of times by shooters all over the country.
Load Development Interpretation
- Thread starter jstanton
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waveslayer
Well-Known Member
I forgot that part, magnetospeed is a Pain in the Butt!!!! I got over it and bought a labradar to get more data
You are shooting groups with it on and measuring group size, that is shooting for accuracy. IMO any group size data with the magneto speed on is null. It's great for measuring velocity but group shooting with it on will be counter productive.
QuietTexan
Well-Known Member
A rough rule of thumb is that a valid ES is ~5x of SD. There's a lot of math behind making that number 5 and not 6, but looking at a normal distribution 99+% of data points happen within 3 standard deviations of the mean, meaning within 6 total standard deviations. Until the two stats start to normalize they don't have much inferential value.
Two things to think about here: one is that ES uses the least possible number of data points - two of them to be exact - and since those two points are the highest and lowest they're the most susceptible to being outliers. That means ES is the weakest possible statistical comparison with the least inferential value.
Second builds on that last point - ES will almost never provide positive confirmation of anything (since to be practical we're limited to reasonable round counts), at best it provides negative confirmation in small data sets. One place this is useful is roughing in a barrel tuner - if you shoot pairs you can say that while the aggregate group of a much longer shot string might get larger than the pair, it can never get smaller than the pair. So you rule out tuner settings that have too large of an ES and move on. That doesn't help you prove any given setting is actually good, to do that you have to increase the number of shots. So I'll sit there and turn the tuner to a setting, shoot two, and either move on if the group is too large, or continue shooting until the group opens up.
Clear as mud?
Stats is very important to shooting, but it's also a very, very easy way to misrepresent information. One problem is that it can set impossible goals because everyone on the internet can shoot a1SD/1ES group... they don't really say it was three shots, or they ignored "flyers". Don't chase a ghost, look at the paper targets and do what they tell you to do.New brass is going to have some case to case inconsistencies, even coming from the best brands. They're manufactured to be very consistent overall but until they're shot there's no telling how each will respond to what happens inside of the case. It can be tough to shoot through all your cases with tight components now, but the second and third firing are probably a better place to get muzzle stats. Then the real crazy happens - SD and ES might start opening up , yet groups will stay consistent if you tune the load right.
Managing muzzle velocity variation is critically important - but very dependent on how far and what you're shooting.
ELR/ more than 1000 yards - very important.
Shooting really small targets/ trying to make first round hits anywhere past 600 yards - very important.
Match shooting where you get to shoot sighters and can re-dial your scope before shooting for score under 1k - not very important.
200 yards - literally will never matter - unless you're making loads so unsafe that you shouldn't be loading at all
JKPhoto
Active Member
Tagging in ...
I can't help but think the Magnetospeed is affecting groups as well as POI. Much like a tuner if it isn't in an area of the harmonics that the barrel likes, it's going to be difficult to get repeatable groups. I wouldn't be too upset at the velocity/ES/SD variances you are seeing with a new barrel and new brass.
In addition to that Berger load data tends to be very conservative. Let your rifle and brass tell you what it likes. Personally I strive for 99-102% case fill and typically have lower deviations in ES (which is much less important as mentioned earlier) and SD.
Here's an example of where you can have low ES and SD but it's definitely not the norm.
Unfortunately it appears to be a wee bit overpressure based on nearly pierced primers, although ejector marks are pretty light to my eyes. Case fill on this one was at 103%.
In addition to that Berger load data tends to be very conservative. Let your rifle and brass tell you what it likes. Personally I strive for 99-102% case fill and typically have lower deviations in ES (which is much less important as mentioned earlier) and SD.
Here's an example of where you can have low ES and SD but it's definitely not the norm.
Unfortunately it appears to be a wee bit overpressure based on nearly pierced primers, although ejector marks are pretty light to my eyes. Case fill on this one was at 103%.
My 26", 8 twist heavy contour 6.5 Creed has two different preferences for where it likes to shoot best, one dirty and one short lived when clean. Keeping it in a happy balance between to clean and to dirty is a matter of shot counting for me. The break in period was a time of inconsistency too.
Thanks Judd! I think I will explore that 41.5 group a little further and see what it does going up to 42.5. Also I am running a Curtis Axiom action with Curtis bottom metal and magazine. For me .025" off the lands is the furthest out I can seat and still fit in the magazine. A Wyatt's may be in my future but for now I will see what it does from .025" and back once I start my seating depth test.
Your right I was putting too much stock in the group size but I also had unrealistic expectations of what my repeatable ES and SD should be. When I saw that 40.7 group ES and SD basically double that threw me off. I think I will explore that upper end node at 41.5 and up to see what happens.
My barrel has about 160 rounds of factory ammo through it. I wanted to break it in before starting load development for it but I get what your saying. Now that I have a more realistic idea of what an acceptable variation of ES and SD for the same load is, I am pretty happy with the results I am seeing so far.
On the subject of brass...lets say after I nail down the charge weight and seating depth and come up with an accurate load that I am happy with based on new brass dimensions, would you do a normal FL resize for this load or would you just FL resize with a shoulder bump of .002"-.003"?A rough rule of thumb is that a valid ES is ~5x of SD. There's a lot of math behind making that number 5 and not 6, but looking at a normal distribution 99+% of data points happen within 3 standard deviations of the mean, meaning within 6 total standard deviations. Until the two stats start to normalize they don't have much inferential value.
Two things to think about here: one is that ES uses the least possible number of data points - two of them to be exact - and since those two points are the highest and lowest they're the most susceptible to being outliers. That means ES is the weakest possible statistical comparison with the least inferential value.
Second builds on that last point - ES will almost never provide positive confirmation of anything (since to be practical we're limited to reasonable round counts), at best it provides negative confirmation in small data sets. One place this is useful is roughing in a barrel tuner - if you shoot pairs you can say that while the aggregate group of a much longer shot string might get larger than the pair, it can never get smaller than the pair. So you rule out tuner settings that have too large of an ES and move on. That doesn't help you prove any given setting is actually good, to do that you have to increase the number of shots. So I'll sit there and turn the tuner to a setting, shoot two, and either move on if the group is too large, or continue shooting until the group opens up.
Clear as mud?
New brass is going to have some case to case inconsistencies, even coming from the best brands. They're manufactured to be very consistent overall but until they're shot there's no telling how each will respond to what happens inside of the case. It can be tough to shoot through all your cases with tight components now, but the second and third firing are probably a better place to get muzzle stats. Then the real crazy happens - SD and ES might start opening up , yet groups will stay consistent if you tune the load right.
Managing muzzle velocity variation is critically important - but very dependent on how far and what you're shooting.
ELR/ more than 1000 yards - very important.
Shooting really small targets/ trying to make first round hits anywhere past 600 yards - very important.
Match shooting where you get to shoot sighters and can re-dial your scope before shooting for score under 1k - not very important.
200 yards - literally will never matter - unless you're making loads so unsafe that you shouldn't be loading at all
My plan was just to FL resize with a shoulder bump of .002"-.003".
Oh its not that bad! Hopefully Santa Clause will bring me a LabRadar for Christmas!!
Yeah I would start at .025 off then and work back to .060 off or so. There's multiple seating depth "nodes" and you'll still be able to find a good one even if you have to be off the lands a little ways.
Jstanton - A "normal FL resize IS a .002 bump. No reason to ever do more unless the round won't chamber due to die not matching chamber well enough. Only then do you have to keep bumping back until brass will chamber - or try a different die.
