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  #11  
Old 12-05-2018, 02:30 PM
recoillug recoillug is offline
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Quote:
Originally Posted by flyrod View Post
The way around that is to fire "round robin" when testing. Suppose you have 3 different things you want to test against each other: A, B and C. Instead of firing AAAAABBBBBCCCCC, fire ABCABCABCABCABC. This will also show you how a barrel that heats up affects each of A,B,C.

One case where this sometimes doesn't work well is with completely different powders. Some powders will foul differently, so changing the type of powder with each round may not tell you what you want to know.

That is what I do when comparing different load variables, but what foxhunter is talking about is comparing velocity differences (variation/SD) when loaded exactly the same. There has to be an error factor associated with sequence (due to heat), I was just wondering how much of a factor this would be.
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  #12  
Old 12-05-2018, 03:03 PM
flyrod flyrod is offline
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It should be the same thing. So if you fire a set of cases and then sort them into fast, medium and slow with chronograph data (or maybe just high and low SD), then you would just reload them for a subsequent test and then shoot batches in round-robin to interleave the sequence.

With F-class there is time to take notes and such. I've had a few shots that seemed worse than the conditions should allow, so I would set those cases apart to inspect later. A few high shots were attributed to donuts this way. I also found one with a significant banana shape. One side of the case must have been much thicker, because the FL die would not straighten it out.
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  #13  
Old 12-05-2018, 11:56 PM
PGW Steve PGW Steve is offline
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20 years ago, I set myself up to do load development at the range. I hated loading 5 of this and 5 of that and then coming home to pull the ones that would be way too hot. I'd bring primed brass to the range and load like that.

At the time, I remember doing a test of firing a shot, then decap, neck size, prime, charge, seat and shoot. Did that about 10 shots with the same case. I really really wish I had taken some notes on this experiment to share!

With that said, I now have a range outside my home and can redo this experiment....in about 5 months when the snow melts and the air doesn't hurt my face. I can charge the cases with even greater accuracy, I have an FX120i scale with autotrickler/dump.

Perhaps 5 cases, fire 5 at individual bulls. Keep the 5 segregated and reload them 5 total times. This will generate five, 5 shot groups with one case used for each group. I can't wait to give this a try. Thanks for the inspiration!
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  #14  
Old 12-06-2018, 03:18 PM
recoillug recoillug is offline
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Quote:
Originally Posted by flyrod View Post
It should be the same thing. So if you fire a set of cases and then sort them into fast, medium and slow with chronograph data (or maybe just high and low SD), then you would just reload them for a subsequent test and then shoot batches in round-robin to interleave the sequence.
While this may be more of an academic exercise than anything else, but it brings up a question I have wondered about. In the example, you indicate firing a set of cases and sorting them into fast, medium, and slow to further test impact of case batches on velocity using a round robin sequence. However, what I'm asking is how much could the initial firing sequence be affecting the initial velocity grouping (fast, medium, slow) in relation to case characteristic? In other words, could the firing sequence be more of a determinant factor influencing initial velocity grouping than case characteristic, or at least a significant confounding factor? I suppose that could depend on how close or how different the various cases may be from each other. Like I say, without hard data to work with, this is purely academic but I do know heat can be associated with increased velocity -- even in the more stable powders.
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  #15  
Old 12-06-2018, 04:36 PM
foxhunter foxhunter is offline
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academic, yes. I fire a fowler shot and then wait 5 minutes between shots and use wind flags and look for the exact same conditions. I would think this would minimize the heat factor.
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