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MD....Inquiring minds want to know: Which chronograph gave the odd result?


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The last Shooting Chrony I owned.


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My thoughts, FWIW, I agree with MD pretty much across the board. There be a tremendous amount of chaos unleashed with the primer pops, and our job is to make the chaos as uniform as possible from shot to shot. Some things are more important than others, but if you fiddle long enough you'll figure out what matters. An example that gave me pause years ago: .338 Win load work up, Shilen DGAM action and barrel properly installed on a quality composite stock. Load 1 goes down range to the 100 yard target and groups about 3", this with an ES of 5 fps. Load #2 follows and has an ES of about 12-13 as I recall, and groups in the 3/4" range. Easy choice that was. Paper is paper, dead meat is dinner.

I like to explore the numbers, but at the end of the day don't forget what the purpose of the drill is....


I am..........disturbed.

Concerning the difference between man and the jackass: some observers hold that there isn't any. But this wrongs the jackass. -Twain


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Then there's playing with seating depth, which often is more important than powder charge.

I load to magazine length or 0.010" to 0.015" off the lands. Get good result at long range (600-1200 yards).

I have been tuning with powder charge and have not at all explored tuning with seating depth.

The reason is I do not fully understand how this method works over the powder charge method, especially if chamber to bore axis is perfect and zero run out on the loaded cartridge.

Can you explain in a few sentences? thanks.

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And when a fella gets this all figured out he ought to start loading BP cartridges for competition. The learning curve is steep. laugh


I am..........disturbed.

Concerning the difference between man and the jackass: some observers hold that there isn't any. But this wrongs the jackass. -Twain


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Hey Dan, do you think that some people here overthink things a little? I believe that John should do a proper advice column: Ask John.
---

Dear John,

I'm having a problem with my chronograph. Or maybe my rifle. Or my components. I'm not really sure.

I own a Savage Axis XP in 308 Winchester - please note, it's not the regular Axis, but the upgraded skull stock and whatever else they put on the XP to make it better. Here's my problem. I just started reloading, and bought a Shooting Chrony, and proper targets from Cabelas. I used to print targets at home on my printer, but decided it was time to work things through scientifically, so I got orange ones.

Anyway, I loaded up seven cartridges and took them to the range. It was really exciting! My first home made cartridges! I set up everything on the shooting bench, including my chronograph. I read at your website - 24 Hr CampFryer - about testing your own reloads. When I shot the first three, all the velocities were different!! I followed the recipe EXACTLY (capital letters added for emphasis). I just don't get it.

My scale isn't cheap! I bought it off of ebay for $30. It's digital!
The powder is all fresh. I think I read somewhere that you shouldn't use powder that's more than 2 years old.
I'm shooting Noslers, not cheap Hornady or Barnes bullets.
I got a Leupold scope. That might be my problem. I read there that Leupolds are junk now.
I bought Lapua cases too!

So what's the deal? Is my chronograph uncalibrated? Is the Leupold affecting the velocities? Should I switch case brands or try another bullet? Woodleighs? Maybe they're dirty and need cleaning?

I'm at my wit's end and ready to chuck it all!



Safe Shooting!
Steve Redgwell
www.303british.com

Get your facts first, then you can distort them as you please. - Mark Twain
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Over think it?

Maybe, lemme think about it. laugh


I am..........disturbed.

Concerning the difference between man and the jackass: some observers hold that there isn't any. But this wrongs the jackass. -Twain


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Originally Posted by Dirtfarmer
I used to be more concerned about low E.S/S.D..'s. than I am now. I've had rounds with less than desirable variations that shot great. I'm now looking more at the target, but realize, E.S. and S.D. values have merit. May be more important at extreme ranges.

Seems to me that Varget has some of the lowest E.S. values and does very well at the target. I can see why target shooters like it. I know I do.

It can be a fickle business, different powders performing differently in different rounds. So, blanket statements may not have a lot of predictive value, opinions here on the Fire, notwithstanding... blush

grin

DF

I read a lot and still do. Made me chase the low ES/SD numbers. Along the way I found I was watching the chrono and saying, WOW this is going to be THE load ( shooting far enough away at paper to not be able to see the group) only to drive down and look and say WTF. The group was horrible. Or at least bad.

Found that often times a higher ES/SD gave better paper groups.

That was probably circa early 90s for me.

Since then a chrono only tells me appx what speed I'm at and allows me to do a bit of calculating to have appx drops when I'm going on out and firing my actual drops for data. I have almost zero use for chrono these days, ALMOST.

The ONLY way, IMHO, to know how a load groups at X distance, is to SHOOT it at X distance.


We can keep Larry Root and all his idiotic blabber and user names on here, but we can't get Ralph back..... Whiskey Tango Foxtrot, over....
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Originally Posted by denton
It actually doesn't require a normal distribution. If special causes like barrel rubs and shooter flinch have been eliminated, so that variation is random, then it will give about the same answer as calculating SD by its definition, the sum of squares. If special cause is present, then the classic sum of squares route will give a higher number.

Standard deviation is a measure of variation.

Range is a measure of variation.

They are different measures of the same thing, and can be converted back and forth. If the subgroups have few items, the conversion is pretty good.

If you are shooting five shots, range is about as good a number as you can get.


No, playing with some numbers here, I'm pretty sure it does require a normal distribution or at least an even spread of numbers across the range. Your assumptions don't hold up in the real world; velocity variation is not truly random and often shows skewed groupings that don't match your assumptions. Too many of the variables that affect velocity end up in groups (like different headstamps) and that makes an assumption of random data unrealistic.

For example, sometimes a first shot is lower velocity than all the rest in a string - the standard deviation is higher compared to another string of numbers with an even spread, even when the extreme spread is the same.

Or, maybe we have two lots of brass that result in different velocity, so we've got two velocity groups in our string - then the standard deviation is even higher with the same extreme spread.

We can't just assume those things don't happen (because they do), and that's why we don't just use e.s. by itself. Of course neither number means much with only 3 or 5 shots except to tell when something really went wrong.

Last edited by Yondering; 10/16/19.
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I appreciate the depth of knowledge and experience represented by All of Your replies, (I'm the OP), and it basically proves to me that ANY statistical information is better (maybe ,only really useful,) with bigger statistics. Back to my simple logic question, before I burn out my barrel; I am trying to find a short-cut around discovering, then weeding-out, the likely culprit of aberration statistics in a small-section analysis of one gun, and one bullet, while fine-tuning, or re-trying a previously successful powder charge, as a way of finding more consistent "predictability" with less wasted experimentation.

I do not rely on low ES or SD as the pinnacle statistic for accurate shooting, but I do see it as a significant sign of accurate reloading. Actually, I too have occasionally gotten my best groups with a wider SD, and that's usually the load I went to the field with. I am assuming here(.., and here's the simple logic part,) that my reload "node" was wider with the wider SD, while still giving me the consistent P.O.I. accuracy I want, thereby offering me a greater range of flexibility and success in my imperfect reloading process.

Small matters, consistent groups across +/- 3% powder charge = Winner (for me)! Most of my really stellar groups have been hard to recreate consistently (but I have had some tantalizingly consistent ones). This is why I continue to struggle along wither ladder tests at my measly 150 yd range. They rule out the the totally useless powder/bullet/rifle combos that the reload manuals and internet statistics say should work great. Does quick-load do a better job at weeding out these aberrations?

Thanks again All!! I really appreciate You gun-nuts taking the time to consider this sort of question seriously. I can easily slip down the rabbit-hole of over-thinking, and it's reassuring to find a full house when I get down there!


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Dunno what you're shooting but ladder tests are useful things.


I am..........disturbed.

Concerning the difference between man and the jackass: some observers hold that there isn't any. But this wrongs the jackass. -Twain


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Do ALL operations and actions exactly the same.

Size concentrically 180 deg.

Weigh bullets/sort.

Weigh brass/sort.

Weigh each powder charge TO the tenth.

Measure exactly.

Seat concentrically 90, 120 or 180 degrees.

Minimize runout.

If using a crimp, crimp concentrically 180 degrees.

If shooting copper, allow copper equilibrium...don't remove copper overcleaning.

Cold bore shot(s).

Wind management.

Use multiple strings if necessary.


Don't ask me about my military service or heroic acts...most of it is untrue.

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Originally Posted by JeffG


My question:
Why wouldn't the best consistency of any rifle/cartridge/bullet combo be the same with any powder that can achieve the same muzzle velocity?


Maybe this was mentioned but barrel harmonics would be my guess.Different powders have different pressure curves which directly effect the way the barrel moves.

Shooters who are serious about the best accuracy buy certain powders that are“Tried and true” . They buy powder in bulk as well. (8 pounders minimum ). They buy bullets by the thousand and enough cases to last the life of the barrel. This is all in an effort to mitigate the effects of changing lots which effects harmonics and consequently having to repeat load development.

Or if you have minimal time to experiment ( like myself ) you also buy in bulk for the same reasons mentioned.


Last edited by SawDoctor; 10/19/19.
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Originally Posted by SheriffJoe
Do ALL operations and actions exactly the same.

Size concentrically 180 deg.

Weigh bullets/sort.

Weigh brass/sort.

Weigh each powder charge TO the tenth.

Measure exactly.

Seat concentrically 90, 120 or 180 degrees.

Minimize runout.

If using a crimp, crimp concentrically 180 degrees.

If shooting copper, allow copper equilibrium...don't remove copper overcleaning.

Cold bore shot(s).

Wind management.

Use multiple strings if necessary.


I can do quite a bit less, and still win matches out to 600 pretty easily against some good shooters. Sometimes we do more than we need.

OTOH I don't shoot BR either.


We can keep Larry Root and all his idiotic blabber and user names on here, but we can't get Ralph back..... Whiskey Tango Foxtrot, over....
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Originally Posted by JeffG
I appreciate the depth of knowledge and experience represented by All of Your replies, (I'm the OP), and it basically proves to me that ANY statistical information is better (maybe ,only really useful,) with bigger statistics. Back to my simple logic question, before I burn out my barrel; I am trying to find a short-cut around discovering, then weeding-out, the likely culprit of aberration statistics in a small-section analysis of one gun, and one bullet, while fine-tuning, or re-trying a previously successful powder charge, as a way of finding more consistent "predictability" with less wasted experimentation.

I do not rely on low ES or SD as the pinnacle statistic for accurate shooting, but I do see it as a significant sign of accurate reloading. Actually, I too have occasionally gotten my best groups with a wider SD, and that's usually the load I went to the field with. I am assuming here(.., and here's the simple logic part,) that my reload "node" was wider with the wider SD, while still giving me the consistent P.O.I. accuracy I want, thereby offering me a greater range of flexibility and success in my imperfect reloading process.

Small matters, consistent groups across +/- 3% powder charge = Winner (for me)! Most of my really stellar groups have been hard to recreate consistently (but I have had some tantalizingly consistent ones). This is why I continue to struggle along wither ladder tests at my measly 150 yd range. They rule out the the totally useless powder/bullet/rifle combos that the reload manuals and internet statistics say should work great. Does quick-load do a better job at weeding out these aberrations?

Thanks again All!! I really appreciate You gun-nuts taking the time to consider this sort of question seriously. I can easily slip down the rabbit-hole of over-thinking, and it's reassuring to find a full house when I get down there!

I may have missed it, but have you stated your goal? what accuracy at what distance and with what gun/type of gun/custom or not etc?

IMHO if you think you had a better load but can't duplicate it, most times you never had that good of a load. Hence some of the threads on 2 -10 shot groups. We shot 22 shot groups in competition and that would really tell you what you had. The one time I had a tube I was working on that produced some 1.25 inch 5 shot groups at 600, I knew good and well it would likely be a hot tube but more like a .5 moa gun at 600 rather than .25 moa or so... even though I had a number of tiny groups. Not enough to be statisical though.


We can keep Larry Root and all his idiotic blabber and user names on here, but we can't get Ralph back..... Whiskey Tango Foxtrot, over....
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Originally Posted by rost495
Originally Posted by SheriffJoe
Do ALL operations and actions exactly the same.

Size concentrically 180 deg.

Weigh bullets/sort.

Weigh brass/sort.

Weigh each powder charge TO the tenth.

Measure exactly.

Seat concentrically 90, 120 or 180 degrees.

Minimize runout.

If using a crimp, crimp concentrically 180 degrees.

If shooting copper, allow copper equilibrium...don't remove copper overcleaning.

Cold bore shot(s).

Wind management.

Use multiple strings if necessary.


I can do quite a bit less, and still win matches out to 600 pretty easily against some good shooters. Sometimes we do more than we need.

OTOH I don't shoot BR either.





Big deal.

We can shoot out to that with an M4. Keep practicing.


Don't ask me about my military service or heroic acts...most of it is untrue.

Pronoun: Yes, SIR !
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