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jwhittin

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About jwhittin

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    Joel Whittington

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  1. Glad it worked out. Thanks for asking the question. I learn a lot in these threads.
  2. I'm going to take a swing at this as a relatively new CRO. The rules recommend collecting samples as randomly as possible. A true random sample of the 300 rounds, across two lots of reloads you intend to use, would result in 4 samples from each lot. That meets the wording in the rule book. I think using 8 rounds from the lot that has not passed a chrono test would be more appropriate to meet the intent of the rules (best way to ensure ammo meets declared PF). I look forward to hearing what the experienced folks say.
  3. The ones I bought were advertised as frames from brand new unfired factory Sig P320s. I checked the serial number at the Sig Voluntary Upgrade Program webpage and they are recognized as being official Sig Sauer products. I guess the dealers realized they could make more money selling them as parts.
  4. I bought two a month ago. Supply is gone. Saw one listed for $100. Found an M17 version for $50 at sigsauerparts (not affiliated with Sig). OP glad you figured out what the problem was. Have you talked to a Sig about the slide? Seems like it should last longer. I can see a barrel going bad at 78k rounds. Can’t hurt to call them. Sig might replace it.
  5. Any update on your issue? Did you solve the mystery? I'm having accuracy issues with my P320 X-Series (GGP slide, Victory barrel, X-series grip) but I'm pretty sure its the barrel (poor fit). Will be troubleshooting more after Mile High Showdown this weekend. Didn't have much time to check it so I have to switch to Limited.
  6. Reread Original post. what do you mean by this? What is the end result? Stove piped round? Is the round nose diving into the ramp? a picture would be helpful. Or a better description.
  7. More likely to be OAL and/or bullet type (shapes). Is there anything you can surmise from what data you have now?
  8. The problem with using only 3 samples is that the variation between measurement sets can make it very difficult to reach conclusions about your Avg Vel and STD with an acceptable level of confidence. If you take 3 or 4 or 6 data sets of 3 rounds each and calculate and compare the statistics (avg vel, STD, spread) for each set, you will see what I'm talking about. The results are all over the map. That is why I did the analysis and determined the Z parameter which relates 8 round measurement results to a confidence level of passing the PF check with the first 3 rounds.
  9. You are correct about the overall process. I just wanted to improve the chance of passing using the first 3 rounds so not to stress out about it.
  10. Per 37, one additional round is used. Could improve your chances or make things worse. It's a gamble. This is why I calculated the Z parameter using only 3 rounds. I didn't want to worry about what happens next.
  11. Exactly!!! and that is the whole point of using the Z parameter and SD, not PF (as explained in my article). The Z parameter is based on the statistics of using 3 rounds for pass/fail (P/F). It takes into account your actual average velocity and SD ( measured using 8 rds) and provides a P/F confidence level as a guide). Once you go below 8 samples, you should use the T or Student distribution or your results will be skewed. Case in point, if you add 1SD to your avg velocity, as you stated the Normal dist tells you 68% will be within +/- 1SD (32% outside). But if the P/F criteria is det
  12. You only need 8 rounds to get a good statistical measurement (avg vel, SD). The question is what do you do with it? How does that relate to an official power factor check? You cant use your measured statistics directly to know if you will pass the official PF check. Here is why and how to use your measurements.
  13. Nothing wrong with the Sig P320 X models.
  14. Shoot what works best for you. Be cautious about trigger work - make sure you know how to do it and keep the trigger safe. Focus on training - recoil management and trigger control are HUGE! A light trigger can sure help but it can't replace this essential skill.
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