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Thread: Chronograph Challenge and chasing ES/SD

  1. #21
    Boolit Grand Master
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    Good point Larry. My jacketed rifle load development is done at 100 yards. Recently, I expanded the range to 200 yards. That is the maximum range I can test at. My ranges could be too short to show much difference in ES. Or, I have been lucky and stumbled into loads that have a "good enough" ES without knowing it. I may have also "stacked the deck" by using good jacketed bullets and Varget for both the .223 and .308...a known accurate powder for those calibers.

    I am tempted to set the damn thing up and check ES. But if I get an ES of 75 fps and am shooting good enough groups do I want to go down the ES/SD rabbit hole?

    Here is an article I found. The data for 250 yards is interesting as I rarely shoot past that range. Both my rifle calibers are listed (.223, .308)

    https://www.recoilweb.com/chasing-mu...ng-152257.html

    Larry, thanks for the info on primers as well. You confirmed what I suspected. My method is "wrong", but it is all I have. I never go past max data as a result.
    Don Verna


  2. #22
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    Per your question, Larry answered it perfectly as I see it. Hope you find that helpful

  3. #23
    Boolit Grand Master jmorris's Avatar
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    It’s another tool in the box. You don’t need to eat healthy and see doctors but there is evidence that doing so can help.

    I loaded for 25 years or so before I bought my first chronograph. I too worked up loads as you describe.

    I suppose it was gun games and having to load my ammunition to a particular power factor was what made me buy my first chronograph. Depending on the game you are disqualified all together or scored so differently, you might as well have been disqualified. So that was a pretty big deal.

    After owning one for awhile, I found them a nice easy way to quantify loads, ensure I was achieving appropriate velocity’s for certain projectiles to work, others to not have a sonic report.

    Not the end all be all of reloading gear but just another tool that is as useful as the owner wants it to be.

  4. #24
    Boolit Buddy 414gates's Avatar
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    Quote Originally Posted by dverna View Post
    If someone would post how they use a chronograph to determine a safe load that would be worth examining.
    A chronograph on it's own can't tell you if a load is safe.

    It can only tell you what the velocity is.

    If you are using published load data, then it's easy.

    Using an unknown powder ? Personally I'd use it for the pot plants.

    It is possible to compare pressures of different loads, you just need to start off with virgin brass. Measure case diameter as close as possible to the extractor groove, or rim. Fire the load, and measure again. This needs a 1/10,000 micrometer.

    This way, you can compare a max known published safe load to your surplus powder load, and this will tell you very precisely how the pressure compares.

  5. #25
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    Quote Originally Posted by dverna View Post
    This is most interesting as it is unexpected. Ballistically, a 100 fps variation cannot effect POI by 2" at 50 meters. Trying to determine why this is happening is making me scratch my head.

    Do you think barrel/action harmonics in a lever action (or at least your 336) have a greater effect than with other platforms? Thus a 100 fps difference has a more pronounced affect than a simple math calculation of POI change due to velocity change?
    Don - To be clear, my measurements concern cast bullet velocities in the range of 1800 - 2100 fps from a pre-Microgroove Marlin 336A used for LAS.

    POI is obviously down to a lot more than simple velocity/trajectory. If is was just about trajectory, the differences over the whole velocity range would be in fractions of an inch at 50 or 100 meters. The actual calculation (Hornady calculator) suggests 0.3" difference per 100 fps per 50 meters for my velocity range. Other issues in POI are recoil, bullet time in the barrel, and no doubt barrel harmonics ("flip"). In the case of the .30-30 levers, I suspect that the effect of recoil across barrel time is the prime suspect.

    For my Savage 99 .30-30 (used for real pigs), the effect is less pronounced, but it is still there. I have only group POI to go on for this rifle, but with 175 gn cast bullet, the difference in scope sight setting between 2200 fps and 2300 fps (LeverEvolution powder - thanks Larry) is 1.5 - 2.0 minutes. That rifle weights 9 lbs with scope and ammo, which might be a moderating factor. Incidentally, this is another plug for the chronograph - I load both 175 gn cast and Sierra 170 bullets to 2300 fps, but need 2.3 gns less powder for the cast than for the Sierras.

    I am not a revolver shooter, but I keep seeing references to the effect of bullet weight on POI - heavier bullets shooting high due to extra recoil in relation to bullet time in the barrel.

    Another example of the perversity of POI is the Lee Enfield rifle. With the same sight setting, Mk VI ammo (215 gn bullet at about 2000 fps) shot higher than MkVII (174 gn at 2440 fps) all the way to 900 yards. Within a string of shots with MkVII, the same velocity effect is evident. Up close, the lower velocity shots would be the high shots in the group and the higher velocity shots would be the lower ones. At the longer ranges the combined effect of short range POI difference and differing trajectory would bring the shots together into a tighter group. This was referred to in target shooting circles as "compensation", and was the main reason Commonwealth target shooters clung so long to the SMLE No4 7.62 conversions. By contrast the P14 and Martini Enfield .303 rifles exhibited "normal" behaviour - heavier or slower bullets shot lower, right from the start.

    Oops - going off thread.
    Last edited by Wilderness; 07-12-2022 at 09:11 PM.
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  6. #26
    Boolit Master Shawlerbrook's Avatar
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    Need is a highly variable word. I just bought one for some load development for my Marlin 250ai. I just think it’s a tool to give me a little additional information when loading for a caliber with not a lot of data in a rifle not common to the round.

  7. #27
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    "This is most interesting as it is unexpected. Ballistically, a 100 fps variation cannot effect POI by 2" at 50 meters."

    Barrel vibration harmonics can and does effect POI. You see it mostly in rifles that have velocity nodes that they perform the best at.
    Last edited by M-Tecs; 06-24-2022 at 08:03 PM.
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  8. #28
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    With powders being so hard to find anymore I like to have the chrony so I can get data from different powders and see if my best accuracy from one powder to the next is all in the same velocity range. And so far that is exactly what I have found with my 03A3 and my AR15. Different powders call for different weights but what works best is the always very close to the same FPS no matter the powder charge. I note all of this in my charge sheets so the next time I don't have to set it all up again. I already know the proper load for whatever powder I have on hand.

  9. #29
    Boolit Master RKJ's Avatar
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    I don't need a 2nd Chronograph (heck, I don't need the one I have) but I like the fact that I can verify the velocities of my loads. I know what the books say the velocity is from their barrels but it's nice to see what I'm shooting from mine.

  10. #30
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    With ladder testing it's a useful tool to find the 'best'/consistent charge. You can fluke into a good 5 shot group with an inconsistent burn that you will never repeat. The chance you fluke into a good 5 shot group that also has a single digit SD that won't repeat is much lower.

    It's also useful for making a drop chart/calculating velocity at X yards. Good luck doing that without a chrono.

  11. #31
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    An interesting observation I've made is the group distribution of shots vs the SD/ES ratio. This observation is not a 100% given but falls into the most often observed category. The more groups (10 shot) of a given load that is fired the more likely the shot dispersion I'll mention will be observed.

    If we observe a group (10 shots) that has an SD/ES ratio less than 25% of the ES we most often see a small cluster of 7 to 9 shots with 1 to 3 shots "out" of that cluster.

    If we observe a group with an SD/ES ratio of 25 - 35% the group, given an accurate load in an accurate rifle under the RPM threshold, we will see a nice tight group with all shots relatively close together. How close is dependent on the accuracy potential (cone of fire) of the rifle. This is the range of SD/ES ratio we should strive for.

    If we observe a group with an SD/ES ration of 35 - 45% the group, given an accurate load in an accurate rifle under the RPM threshold, we will see a group that is not the best for accuracy potential (cone of fire) of the rifle such as a 2" group in a 1.25" capable rifle. However, the shots will be pretty evenly distributed about the group and while not particularly "accurate" it may still be useful. I'm coming to think some powders are more prone to this than others.

    Again, this may be observed with just one group (10 shots) fired and maybe not. Fire several 10 shot groups with the same load in the same rifle and more than likely the pattern commensurate with the SD/ES ratio will become observable. Of course, the adverse effects of wind and called flyers must be taken into consideration.

    In my opinion the reason for such distribution patterns is the closer the SD/ES ratio falls in the 25 - 35% range the more likely the bullet exit from the muzzle is at the same barrel node location. Of course, the heavier, stiffer barrels have less barrel "node" movement so the shot distribution may be less. The above is most noticeable in thinner sporter barrels using heavier cast bullets with faster velocities because they cause a larger barrel "node". Just my opinion on the "why" this is observable.
    Larry Gibson

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  12. #32
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    Larry, that is an interesting piece of information. A lower relative SD, may be detrimental?

    If I understand correctly, a load with an ES of 50 fps and SD of 10 (20%), may not be as good as a load with the same ES but a SD of 15 (30%).

    Is the trend you observed the same with jacketed bullets?
    Don Verna


  13. #33
    Boolit Master 15meter's Avatar
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    Best use of a chronograph was a tumble test 25+ years ago, a couple of guys were on the range with a chronograph they had borrowed from a buddy.

    These guys were HARD core trap shooters. Their definition of an accurate rifle was hitting an 8" paper plate at 100 yards the week before deer season opened.

    I had no idea why they wanted to fool with it other than it was one of the first compact chronographs available and they wanted to play with a new toy.

    They set it up and shot a couple of deer rifles over it and were having fun. Until one guy remembered the box of Remington Accelerator ammo he had in his truck. Don't remember if it was 30-06 or 30-30.

    For those unaware of Accelerator ammo, Remington used to load both 30-30 and 30-06 with .223 sub-caliber bullets in sabots. They did something silly like 4000+ in 30-06.

    Well, the Accerator's got loaded into the gun and the first one was touched off.

    And the chronograph did an absolutely beautiful triple somersault(backflip?) down the range when the sabot hit square in the digital display.

    It would have been interesting to hear what the owner of the chronograph had to say to the rummies when they returned his chrono. He had a reputation of having a bit of a salty tongue.

    I've got a chrono that was given to me by a friend, it was his dad's and he was never going to use it.

    It's about time to get it out and take it to the range. Sky screens are set on ten foot center to center.

    And you have to get out a paper manual and deal with base 8 numbers and conversions to get feet per second of each shot.

    That'll freak out the young pups on the range.

  14. #34
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    In rifles, I use it to determine M.V. to do drop calculations. In handgun, it's pretty much the same thing for the hunting revolvers, but to check for "Major" performance in .38 Super and .45 Auto. ES & SD both seem to make more of a diff with pistol/revolver ammo than with rifle rounds. <shrug>
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  15. #35
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    Quote Originally Posted by 414gates View Post
    A chronograph on it's own can't tell you if a load is safe.

    It can only tell you what the velocity is.

    If you are using published load data, then it's easy.

    Using an unknown powder ? Personally I'd use it for the pot plants.

    It is possible to compare pressures of different loads, you just need to start off with virgin brass. Measure case diameter as close as possible to the extractor groove, or rim. Fire the load, and measure again. This needs a 1/10,000 micrometer.

    This way, you can compare a max known published safe load to your surplus powder load, and this will tell you very precisely how the pressure compares.
    When I get a certain velocity for a given charge weight then get a roughly proportional increase in velocity for an increase in powder charge, it SUGGESTS that I'm still in the "safe zone" of the work-up. If I go up on charge weight and get a very small increase, NO increase, or even a DECREASE in velocity, that suggests to me that further charge increases are likely to unsafe, and I should back off.
    For in much wisdom is much grief: and he that increaseth knowledge increaseth sorrow. Ecclesiastes 1:18
    He that troubleth his own house shall inherit the wind: and the fool become servant to the wise of heart. Proverbs 11:29
    ...Verily I say unto you, Inasmuch as ye have done it unto one of the least of my brethren, ye have done it unto me. Matthew 25:40


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  16. #36
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    I have found this to be mostly true. I also have seen the NO increase, or even a DECREASE in velocity with increased charge weights. I don't understand the why and I get a headache trying to understand that one.

    https://www.shootingtimes.com/editor...owder%20charge.

    There is a better way to work up a safe load. While most of us can't measure pressure, we can readily measure bullet velocity. The only special equipment you need--an accurate chronograph--is well within the means of most handloaders.

    I first read about the velocity-to-charge (V/C) ratio several years ago in a loading manual published by the Somchem Ballistic Laboratory in South Africa. Simply stated, it's the bullet velocity divided by the propellant charge weight. The author was Johan Loubser, who is now the ballistician at Western Powder in Montana.

    I met Loubser nearly 10 years ago in the Accurate Powder booth at the SHOT Show. The South African native struggled to effectively communicate with this ol' Southern boy. Eventually, he was successful in teaching me a few things about reloading. Fortunately, when Western Powder acquired Accurate a few years ago, my friend was part of the package.

    Before immigrating to the U.S., Loubser was the ballistic specialist at Somchem's lab near Cape Town. The company's loading booklet included Loubser's insights on various ballistic performance parameters in addition to the usual load recipes. Promoting the quantitative premise of "if you don't measure it, you can't manage it," he offered a relatively simple method to help shooters assess handload performance.

    First, assemble five rounds using the minimum powder charge suggested by your reloading manual. Next, fire them to determine the average velocity. Then calculate the handload's V/C ratio and compare it to the V/C values derived from recommended load data in your loading manual. Of course, you must compare apples to apples--same powder type, equal barrel length, same weight bullet, etc.

    If the calculated V/C for your handload is higher as compared to the ratio derived from the load manual data, then your ammo/firearm system is generating higher pressures. You may hit the maximum load for your rifle before reaching the maximum charge weight indicated by the manual. Conversely, if the V/C ratio is lower, your system is operating at relatively lower pressures. In order to achieve maximum velocity, you may have to exceed the recommended maximum powder charge.

    Loubser stated the average V/Cs for charge weights within the recommended start and max range should be almost constant. As you increase the charge further, both pressure and velocity change from a relatively linear to an exponential progression. He refers to this as the dynamic V/C range (see the graph on page 28). When the dynamic V/C exceeds 1.5 times the average V/C, pressures have become unstable, and you should back off the powder charge.
    Last edited by M-Tecs; 06-25-2022 at 02:05 AM.
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  17. #37
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    "I have never been able to understand "ladder load development" either and that needs a chronograph." Don Verna

    I would argue your assertion. As I recall, my first exposure to "ladder load development" was an article explaining the process. The thrust of the article was that a chronograph was NOT necessary, results could be evaluated by point of impact. Small deviations in powder load, at some level, would give points of impact that were close together, indicating a charge that produced barrel harmonics favorable to accuracy.
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  18. #38
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    Every shot tests the shooter. It does not matter that the reloads have been made to exacting standards, barrel harmonics are compatible, the gun is "inherently accurate", use of a sturdy rest (always - they are everywhere), measurable "statistics", such as ES (bs), are "small", etc., EXCEPT to increase shooter confidence!

    Shooting is an equation in MANY variables. The LEAST consistent variable is the shooter himself. Practice, practice, practice makes perfect.
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  19. #39
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    Quote Originally Posted by dverna View Post
    Larry, that is an interesting piece of information. A lower relative SD, may be detrimental?

    If I understand correctly, a load with an ES of 50 fps and SD of 10 (20%), may not be as good as a load with the same ES but a SD of 15 (30%).

    Is the trend you observed the same with jacketed bullets?
    A lower SD is not necessarily "detrimental". A low ratio of SD to ES, as in your example (SD 10 fps to ES of 50 FP) possibly indicates something may not be consistent with that load. The SD is simply saying the velocity of 8 shots +/- fell within 10 fps of the average velocity. The remaining 2 shots+/- fell within the 50 fps ES.

    First let me say that I'm referring to ratios based on 10 shot test strings. A 3 or even 5 shot chronograph test with attendant SD/ESs is essentially meaningless with regards to the actual SD/ES.

    Is your example good or bad? If you have tracked the individual shots on target and the 2 shots went to group and it is an acceptable group for the rifle being tested, then the load is probably ok.
    If the 2 shots were out of the group or even on the edge of the group that is indicating the load may not be the best.

    However, remember what I said about "test to test variation" of the same load and not I spoke in past tense of the test data. Chronographing three consecutive 10 shot tests of the same load will, no doubt, give three different average velocities, SDs and ESs. In initial testing if we select one or more loads to possibly use then a series of three 10 shot tests with each should be used before the final selection. The load with the three closest Average, SD and ES will then be the one most consistent internal ballistic. The on target results will tell you the external ballistic consistency. More than likely the load with the best internal ballistics will also give the best external ballistic results, I.E. the best groups. That testing will then tell you, with about the highest level of certainty, what the average velocity, SD and ES (+/-) of that load will be out of your rifle.

    Yes, the trend is the same for jacketed bullets.

    Again, let me reiterate, this is not a "rule" or "theory" but is just an observable trend based on the observation of thousands of test groups in various rifle of different calibers using both cast and jacketed bullets. One must have the shooting ability from a solid bench with solid rests and a rifle capable of very good accuracy. For example, using a milsurp rifle with issue sights having a frosted or corroded barrel and milsurp bullets (pulldowns) would probably not be a good test to observe this trend. Neither would be using a lever action with open sights. However, the same test procedure will still give you the "best" load for either of those rifles. Whether or not you "need" to find that "best" load is simply a personal choice and is up to you.
    Last edited by Larry Gibson; 06-25-2022 at 10:54 AM.
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  20. #40
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    Quote Originally Posted by William Yanda View Post
    "I have never been able to understand "ladder load development" either and that needs a chronograph." Don Verna

    I would argue your assertion. As I recall, my first exposure to "ladder load development" was an article explaining the process. The thrust of the article was that a chronograph was NOT necessary, results could be evaluated by point of impact. Small deviations in powder load, at some level, would give points of impact that were close together, indicating a charge that produced barrel harmonics favorable to accuracy.
    Yes, a chronograph is not needed when using the "ladder" test, either the Audette Ladder test or when incrementally testing (erroneously referred to as "ladder testing"). Both methods can be used by assessing the groups on target.

    The Audette Ladder test is a limited specific test for a minor variation in charge weight of an already developed load at/for a specific range, usually in the area of 600 - 1000 yards. The Audette Ladder test is not intended to be used for load development. Some claim some mystical ability to "read" on target results and 50 or 100 yards using the Audette Ladder to develop loads. It has not been proven and, most often, when thoroughly tested proves to give erroneous results based on those mystical assumptions. Where it fails is it does not consider the cone of fire (group size at a given range) and random shot dispersion within that cone of fire. When testing at a known long range with an already developed accurate load using the Audette Ladder method with subtle charge weight variances different or the same point of impact can be detected. Detecting those variances is what Audette developed the method for, not for load development.

    Incremental load test is what should be used to develop loads for rifles and handguns. It is the tried and true method developed well before my time. It is the method recommended in most every loading manual ["start low and work up, etc.]. Incremental load testing to develop a load was used for many, many years without the use of a chronograph. Loads were developed using "pressure signs" and groups size. With the advent of the readily usable chronograph with sky screens in the early '70s by Oehler affordable chronographs became a useful tool to further knowledge of what the load was actually doing. Through proper use of the chronograph during incremental load development the best load for a use can be much quicker with less expenditure of time and components. It also can give a much higher confidence level that the load is a good one.
    Last edited by Larry Gibson; 06-25-2022 at 01:41 PM.
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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check