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What length barrel?Factory Tikka 223
75gr ELDM over N140. Around 2870fps on chrono
20 shot group.
Pretty happy with this result.
22”. Stainless T3X liteWhat length barrel?
How many grains N140?Factory Tikka 223
75gr ELDM over N140. Around 2870fps on chrono
20 shot group.
Pretty happy with this result.
That’s book max at 25grs. I think I had some loaded at 24.5grs too mixed in there.How many grains N140?
And here is my dad’s. He shot three groups of 10 one for each of the bullets.Super exciting and cool to get to do with your Dad. Consider using extreme spread (ES) instead of mean radius (MR). MR really doesn’t tell us anything…you need to see the targets to understand that group size. We really only care about our worst rounds when it comes to making a shot hunting. You can also have a great sounding MR with a bad ES, and a great ES with a bad sounding MR.Got my dad a tika for Christmas
It’s a 243 with an eight twist in the process of trying different load combinations now first thing we did was test bullets each of us shot groups with the 112 match burner, the 108EDM, and the 108 elite Hunter below is my testing
The first image is 8 x 112 mb, 15x 108 eldm and 12 x 108 eh
The 108 eldm is best with a Mr of .39 for my 15 shot group and .34 Mr for my dads 10 shot group
View attachment 1023797 And here is my dad’s. He shot three groups of 10 one for each of the bullets.
Next step find max pressure for the 108 eldm with h4350, h1000 and h4831sc



How many grains of 4831?Doing some testing with the new 20” 1:8 243. 100 yard groups using H4831 sc, starline brass, and cci primers
View attachment 1022752
Super exciting and cool to get to do with your Dad. Consider using extreme spread (ES) instead of mean radius (MR). MR really doesn’t tell us anything…you need to see the targets to understand that group size. We really only care about our worst rounds when it comes to making a shot hunting. You can also have a great sounding MR with a bad ES, and a great ES with
Spoken like a true egg headI don’t think that’s true. We can assume that bullet distance from center or radius is a normal distribution, mean radius will then converge and on the infinite data set result faster than es . Both are helpful
But as a single number Mr is more useful. Mr and standard devistion on the independ radii combined by doing Mr + 2 *sd . Will
Give you the single best number but having done this a bunch of times what your realize is that your sd scales with Mr. So you almost never a Mr go and sd go down ( this would mean a normal looking group vs a group that looks like a ring for example )
And so Mr is great the problem with es is that it doesn’t give you a good idea what most shots do and is very easily driven by shooter error especially with larger group sizes
Super exciting and cool to get to do with your Dad. Consider using extreme spread (ES) instead of mean radius (MR). MR really doesn’t tell us anything…you need to see the targets to understand that group size. We really only care about our worst rounds when it comes to making a shot hunting. You can also have a great sounding MR with a bad ES, and a great ES with a bad sounding MR.
Spoken like a true egg head
It’s the outliers that lose matches and miss or wound game

It's a rhetorical question. Obviously, the group on the left is more precise and will yield a higher hit rate on a smaller target (provided you zero correctly). But, by your preferred metric of ES, these groups are the same. MR would show these groups are different. MR uses data from every shot in the group, rather than just the most extreme 2. ALL samples will have outliers provided enough shots are taken.View attachment 1024311
Which group is more precise? Stated differently, which will yield a higher hit rate on a smaller target?
It's a rhetorical question. Obviously, the group on the left is more precise and will yield a higher hit rate on a smaller target (provided you zero correctly). But, by your preferred metric of ES, these groups are the same. MR would show these groups are different. MR uses data from every shot in the group, rather than just the most extreme 2. ALL samples will have outliers provided enough shots are taken.
The load on the left will put more shots closer to POA. We happened to get a big outlier in this example. They both have the same ES (according to my sketching abilities). MR tells you this story where ES doesn't. Agree that if you want to characterize the effective accuracy of the system, you need to look at mean + 2-3sd radius OR ES of a meaningful shot count. As I've discussed many times before, tracking individual shot radius data and using mean + sd method will get you to the "correct" or "true" answer in fewer shots than ES method. However you can get the "correct" answer with both methods.Which one tells you what size target you can actually hit on demand?
As stated, hunting is “worst shot”- not “average of best”.
Which one tells you what size target you can actually hit on demand?
As stated, hunting is “worst shot”- not “average of best”.
“On demand” is a statement of probability (99% chance, 99.999% chance, etc), which technically only MR can address, as ES doesn’t offer predictive power.
It’s semantics in practice though because the ES and 3*MR of a reasonable group are roughly equivalent, so you can use either to prepare for “worst shot”. Agree that only using the MR is being overly optimistic to a fault.
But if you could only know one quantity of a system, MR or ES, the former is better because you can derive the latter (along with much more), but the reverse is not true.