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1st Chrono Results & Questions...


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Because if your standard deviation is good (less than 10 is in this ballpark for me) then you can load to 870 FPS with a 147gr bullet if you're looking for your "minimum to make power factor safely.

850fps + 10 + 10 = 870 FPS 

That puts you at 127.8 PF - with very consistent ammo, you're correct sir, you have enough cushion to be statistically quite safe.

However most of us don't shoot 132-135 PF ammo because we want the cushion, it's just the reason you see repeated online.

The gun runs more crisply with a few extra FPS behind the slide's cycling, your split times are freaking identical with a buttery soft 135-147 grain bullet already, and it tends to be more accurate ammo with heavy 9mm bullets.

(Although higher PF ammo being more accurate is anything but a universal rule. You always have to develop your own load for your gun.)

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On 11/24/2016 at 8:54 PM, MemphisMechanic said:

Because if your standard deviation is good (less than 10 is in this ballpark for me) then you can load to 870 FPS with a 147gr bullet if you're looking for your "minimum to make power factor safely.

850fps + 10 + 10 = 870 FPS 

That puts you at 127.8 PF - with very consistent ammo, you're correct sir, you have enough cushion to be statistically quite safe.

However most of us don't shoot 132-135 PF ammo because we want the cushion, it's just the reason you see repeated online.

The gun runs more crisply with a few extra FPS behind the slide's cycling, your split times are freaking identical with a buttery soft 135-147 grain bullet already, and it tends to be more accurate ammo with heavy 9mm bullets.

(Although higher PF ammo being more accurate is anything but a universal rule. You always have to develop your own load for your gun.)

Thank you for the additional understanding, it all makes more sense the more it is discussed.

I had a chance to chrono 20 rounds each yesterday (as suggested) with loads of 3.2 & 3.4 gr of titegroup - 145 gr Acme rn coated - 1,155 OAL

The first string of 20 w/3.2 produced the following results:

914 Hi

879 Lo

896 Av = 129.920 PF

35 ES

9 SD

Second string w/3.4 gr titegroup:

945 Hi

909 Lo

933 Av = 135.285 PF

36 ES

8 SD

This was an outdoor session and my CE ProChrono seemed to work flawlessly.

Although the single digit SD numbers seem pretty good as I understand, I am unsure if the ES numbers are acceptable?

I will try to get to the range over the weekend and shoot for groups testing for accuracy. I did however want to ask if when you test of accuracy is it recommended to shoot with some type of support or just regular standing free style?

Thanks, hope all are able to enjoy a long Thanksgiving Weekend!

IGG

 

 

 

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Well great! You now have two recipes you know will make (an irrelevant pinch under) 130 PF or 135 PF. 

You also have the option of loading to 3.3 gr and reasonably expecting 132-133 PF as well.

This is why loading a "ladder" to develop a new recipe is preferable.

Freestyle vs bagged in? That depends how good you are at shooting freestyle groups. I'm no bullseye shooter and can't get smaller than about 4-5inches no matter what I do. So I shoot with the gun "bagged in" atop my range bag. I do a 6 o'clock hold like a bullseye shooter too, with a black stick-on bullseye target. The gun will shoot tighter groups that way IMO - and they'll obviously be low of center.

6 o'clock hold:

http://www.odcmp.org/0907/usamu_sightpicture.asp

I'm trying to find out what that ammo is capable of through my gun, and I won't know if one OAL or one charge weight shoots 2" groups and another shoots 5", if I shoot it freestyle. Human error will hide it.

Also, don't be afraid to try multiple passes to shoot a tight 15-25yd group if you have never done it before. 

 

Edited by MemphisMechanic
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7 hours ago, MemphisMechanic said:

Well great! You now have two recipes you know will make (an irrelevant pinch under) 130 PF or 135 PF. 

You also have the option of loading to 3.3 gr and reasonably expecting 132-133 PF as well.

This is why loading a "ladder" to develop a new recipe is preferable.

Freestyle vs bagged in? That depends how good you are at shooting freestyle groups. I'm no bullseye shooter and can't get smaller than about 4-5inches no matter what I do. So I shoot with the gun "bagged in" atop my range bag. I do a 6 o'clock hold like a bullseye shooter too, with a black stick-on bullseye target. The gun will shoot tighter groups that way IMO - and they'll obviously be low of center.

6 o'clock hold:

http://www.odcmp.org/0907/usamu_sightpicture.asp

I'm trying to find out what that ammo is capable of through my gun, and I won't know if one OAL or one charge weight shoots 2" groups and another shoots 5", if I shoot it freestyle. Human error will hide it.

Also, don't be afraid to try multiple passes to shoot a tight 15-25yd group if you have never done it before. 

 


Ok next step. I will make some 3.2, 3.3, & 3.4 then go shoot for best groups out of those three right? How many are usually shot per load for grouping purposes?

I'm not as steady as I use to be so I will shoot bagged in as well.

Does "multiple passes" indicate shooting the same distance several times? And am I starting at 15 and progressing to 25 or just picking a distance some where in between those distances?

You also indicated most of you don't shoot at the 132 - 135 PF, what do you shoot at? And will I not be able to achieve the most accurate loads within the ranges I am currently working on?

At 3.4 do I need to be more conscious of nearing max pressures? My data shows 3.6 max however that is for a 147 grain and I'm shooting 145 gr?

So without regard to a PF I would find the most accurate load for my gun by running the ladder and shooting groups?

I'm guessing I will see a difference in accuracy and my gun running better as I was shooting 3.2 gr till now with plated which was probably around a 115 PF?

I know I still have much to learn however I thank you all for helping me get going in the right direction!

IGG

 

 

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Somewhere between 129 and 135 is what most USPSA and IDPA guys shoot. In my experience anyway.

I like 133ish so if 3.3gr groups well, I'd call it good enough and use that.

Accuracy testing is... whatever you're comfortable with. I use lower A-zone at 25yds every time. But might shoot multiple groups of 10 rounds to make sure a poor group wasn't my fault.

If you're happy with a 10 yard group in the head of the target, then use that. Whatever gives you confidence in the load , or proves to you that tweaking it will be needed. ;) 

Edited by MemphisMechanic
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On 11/24/2016 at 8:22 PM, jwhittin said:

Brooke, 

Why don't you use your STD as explained above? As I point out, if you don't know your STD you can fail at any time if you just add a few PF points OR your chrono is off.  

Just curious. 

Because the SD I get on my chronograph data is for that chronograph and the environment at the time of the test. It means little in another test. I have no knowledge of the environment and chronograph that I might encounter at a match. Statistics are great, I'm actually an engineer, but they only apply to the test as run. I have to assume that my limited data set is the smallest data set that will be encountered so I have to allow for a greater deviation to occur at a match chrono. My experience is that 132pf (if obtained in my test with an SD of 10 or less) will pass every time I have been tested and frankly I cannot tell the difference between 125 and 132 on recoil. Maybe you guys can or maybe you're hallucinating. Not my call.

There is a lot of talk about accuracy of powders, loads, pistols, bullets, target distances,etc., but I'm not shooting bullseye. Also I see very few 25 yard and longer targets in IDPA or USPSA. Reasonable accuracy at 7-15 yards is all that is needed to succeed. Shooting at reasonable accuracy, the fastest guy wins every time in hit factor scoring (major or minor) and even in time plus scoring with the new IDPA scoring proposal. You cannot be accurate enough to win if you shoot slow, but you can win by shooting fast with some kind of reasonable accuracy. I don't think obsessing on the minor differences in loads and components at 25 yards is the best way to spend your time, but that's just my opinion.

There is a thread on another forum where a guy is wringing his hands at how someone with 25 mikes in a USPSA match beat him (him being fairly accurate I assume). It's simple, the guy with 25 mikes on one stage had a gun failure and zeroed the stage. That same guy beat the crap out of the hand wringer on speed in every other stage on the match.So  what if you get 2 charlie's or even 2 deltas on every 25 target in a match....just get'em fast and move on. Go out and shoot fast. Don't stumble around on trivial problems.

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SD is the most important number in determining your loads ability to safely make PF no matter where it gets tested. 

Yes, chronos vary, but usually not enough to matter if you have a good PF cushion with a nice tight SD.

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Great discussion points Memphis and Brooke!  I agree, you have to build up your load for reliability and reasonable accuracy too. No need to go into the minutia, just work up a load that is reliable and reasonably accurate and focus on training and improving your skills (instead of whining) (I completely agree!).    The statistical approach is just a place to start which is based on science instead of hearsay (that was my impetus to begin with).  We still need to make adjustments for the unknowns or the reasons just mentioned.   I do know people that consistently measure SDs in the sub 10 fps and they are just not comfortable running that tight so they bump it up to 3*SD.  I agree, most people can't feel the diff between 125 and a 132 PF. 

Brooke – Sounds like you do check your SD regularly.  That’s important.  I disagree with your notion that use of the SD is only a point solution. In fact the SD is the sample variance and is a proven way to make sound judgements (inferences) about the performance of your reloads.  Then we have to apply our knowledge and experience to make adjustments based on the differences between our baseline SD and match conditions (difference in temp, humidity, altitude, etc.,). I think we are saying the same thing just in a different way of looking at it.   Also note, there will be very little difference in SD between chronos (typically 1 to 2 fps but many are within tens of fps).   http://www.appliedballisticsllc.com/Articles/ChronographChapter.pdf 

Off to practice!

Edited by jwhittin
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21 hours ago, MemphisMechanic said:

Somewhere between 129 and 135 is what most USPSA and IDPA guys shoot. In my experience anyway.

I like 133ish so if 3.3gr groups well, I'd call it good enough and use that.

Accuracy testing is... whatever you're comfortable with. I use lower A-zone at 25yds every time. But might shoot multiple groups of 10 rounds to make sure a poor group wasn't my fault.

If you're happy with a 10 yard group in the head of the target, then use that. Whatever gives you confidence in the load , or proves to you that tweaking it will be needed. ;) 

Thanks Memphis, thanks for hanging in there with me. I wanted to run some rounds tonight to shoot GADPA tomorrow night. Following your lead I zeroed in on a single load then dumped 10 loads in a pan for a good average and it was .1+ of the single charge weight... I adjusted the 10 load for a total of 33.1 and went with that. I suspect in reality this might mean I'm really closer to the 3.4 based on the single charge test weight I put across my chrono on Friday? If this is so then that should be about 135 PF. I 'll shoot it tomorrow night. I might be able to go shoot bagged in on Tuesday for lunch then adjust for IDPA Wednesday night,

Overall it is a good feeling to finally know I am headed in the right direction.

Much appreciated!

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