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After months of being completely baffled by the seemingly random, high extreme velocity spreads I've been getting, I think I've finally figured out whats going on! I don't like it, but it is what it is.

And, read on, patience, this is more than just my reloading and my reloads - there's some pretty pertinent information here.

The problem:
First a look at the problem; this is a typical. Three different days, the same charges, the same bullets, the same brand of cases, the same primers, the same powder charges, the same seating depth. Five different charges (as shown), five shots per charge. Five isn't enough BTW :image035:



Notice the ES's. In the top table, the low ES's occur in the higher charges. It changes a bit, i.e. ES's are higher overall in the middle table, but notice the last table - the ES's are essentially the opposite of the first table! :blink:

Even stranger is the middle charge is pretty consistent, then on the 28th, that same great looking charge, 24.2 gr, gave an ES of 66 fps - that's what's been driving me zonkers :ticking:

So that's the problem - so what's the answer???

The answer:
The answer, not the solution, is, that's about as good as it's gonna get within the loading process I'm using. Why do I think that?

I took the umpteenth look at Johnny's Reloading Bench YouTube videos. I picked parts 2 & 4 because that's where he was using A2520 powder, 77gr SMK bullets, and he measures velocity, SD, and group sizes for all loads. Furthermore, he shoots 5 shots per charge. So, for the first time, I decided to look at his results really close.

He only lists SD, so I would have to synthesize the ES from the SD. Looking at my ES to SD ratios and another guys ES to SD ratio, i.e. what you get when you divide the ES by the SD. He got around 3.0 as an average. My average is closer to 2.5, so I used a ratio of 2.8 to synthesize Johnny's ES's from his SDs. Not precise, but quite good enough to be indicative.

So here's Johnny's stats. And, he also measured some Nosler 77 gr Custom Competition bullets so I included those as well. And, he tested the same bullets with CFE 223 so I included that too. I came up with 20 charges as shown in the table below:



I know that's a ton of stuff to look at, so just look at the ES's - notice they run from 31.6 fps to 87.4 fps - and everything in between. At this point, I could show you all kinds of charts, etc. but to spare you from that, I'll simply point you to the following table. What the table tells us is what percentage of the ES's are above the top numbers. For example, what percentage of the groups had an ES of 50 fps or more? Simply look at the top row of numbers, find 50 and the number right under 50 fps, is the percentage of groups that had ES of 50 or more. So from the table, 60% of the groups had ESs of 50 fps or more.



What's really revealing is that almost a third, 30%, of the groups had an ES of 65 fps or more! Almost half of the groups had an ES of 55 fps or more.

OK, same thing with my data from above - only 15 groups instead of 20 however.



Some comparative observations - and this is not in any way intended to be a criticism of Johnny. What the intent is, is to show that two people, me and Johnny, testing very similar loads, completely independently got very similar numbers. Also, it suggests that the details I go through to reload does have the effect of lowering numbers.

  • my low ES is 12 fps; Johnny's low is 31.6 fps
  • my high ES is 73 fps; Johnny has three groups with ES's of 80.6, 83.4, and 87.4 fps
  • 53.3% of my groups had an ES of 45 fps or less; 55% of Johnny's groups had an ES 55 fps or less
  • 40% of my groups had an ES above 50 fps; 60% of Johnny's were above 50 fps
Having said all this, I feel confident to conclude that my ESs are by no means unique since very well documented results from Johnny show very similar results.

And I could be completely comfortable with this, except I know that there are several premium ammo brands that will produce much better numbers. How can rounds mass produced in the millions be so much better than meticulously hand loaded rounds? Oh, this is strictly for the .223/5.56 caliber.
 

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I see there isn’t a huge change in your SD after each firing. What changed there?
 
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I see there isn’t a huge change in your SD after each firing. What changed there?
Headed to the range in just a minute. I'll have to get back to you.
 
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I see there isn’t a huge change in your SD after each firing. What changed there?
I'm lost??? What are you seeing? Thanks!
 
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Well...we have to be careful here, but here's my numbers for today. This is with a Faxon 16" Heavy Flute barrel, Trek T suppressor, Vortex 4-16x Scope, Hornady 75 gr BTHP bullets, new Hornady cases, neck tension with a 0.245 bushing only, i.e. no expander, and five charges of Varget separated by 0.4 gr.

Notice the ES's - 38, 12, 26, 31, and 12 fps - just outstanding.



Accuracy was good too. Three of the five shot groups had amazing four shot groups with a single outlier preventing it from being amazing five shot groups. The upper, far right dot outlier is on me, I just shot it wrong. That's the only one I can claim blame for.



But, I've seen this sort of stuff many times before; if I can do this two more times, I'll start to believe :biggrin2:
 

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I'm chuckling, because when I wrote in another thread that engineers would design forever and ever, amen, in an attempt to get everything absolutely perfect...........I was thinking of you and your reloading project(s).

Not criticizing anything in any way - just remarking on the nature of the beast. Although I didn't go into any kind of engineering, I did inherit (absorb) a lot of the traits from my father. It drives my poor husband NUTS.
 

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I'm lost??? What are you seeing? Thanks!
In the past, each time you would shoot, your SD would get higher and higher. On the charts you posted in this thread, your SD at 24.2 which has been a good charge for you, remained pretty consistant, only increasing by about 5fps from the first to third firing.
 

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In the past, each time you would shoot, your SD would get higher and higher. On the charts you posted in this thread, your SD at 24.2 which has been a good charge for you, remained pretty consistant, only increasing by about 5fps from the first to third firing.
Ahhh, I see. :yup:

Unfortunately, as I've seen happen so many times, the very next day, that same 24.2 charge produced an ES of 66 fps - that's the kind of thing that's been driving me zonkers :ticking:
 
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Ahhh, I see. :yup:

Unfortunately, as I've seen happen so many times, the very next day, that same 24.2 charge produced an ES of 66 fps - that's the kind of thing that's been driving me zonkers :ticking:
I just went back and looked at your other thread. It looks like the answer to my question is simply that your lowest SD was higher than your lowest in the other thread. I was thinking they were actually higher in the other thread that I was thinking of.
 
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