Probability and Statistics, Work up sample size

Discussion in 'Handloading and Reloading' started by d31tc, Oct 26, 2021.

  1. d31tc

    d31tc Member

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    Catchy headline, I know. Fortunately it peaked your interest and you opened the post and it didn't send you cowering to a corner remembering nightmares of college and questions about somebody choosing two non negative integers X and Y and secretly writing them on two sheets of paper. The distribution of (X, Y) is unknown to you, but you do know that X and Y are different, with probability 1....

    Anyway, I'm back from my corner now. So with limited reloading supplies, how comfortable are you with working up a load to a bullet manufacturer's maximum published load using minimal data points? For instance, starting 1 grain back on a 69 grain max load and working up from 68.0gr powder, looking at the case, primer and velocity. Good to go, then try 68.5 grains, again looking at case, primer and velocity. Good to go, then try 69 grains, again checking case, primer and velocity. Good to go - load up 20 and confirm zero and ballistics for your hunting rifle, monitoring each shot for pressure signs. That's kind of where I am at.

    It seems 1 data point at a particular charge isn't the most reliable sample size, however, I figure the manufacturer has way more than that in their tests. Has anyone here experienced a serious issue (kaboom) loading a max published load, when taking care with proper loading procedures (published C.O.A.L., full length resize, published primers, newish (once fired) inspected cases, etc.)?
     
  2. EricBu

    EricBu Member

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    Meh, your gun, your fun. If I was in a situation with limited supplies, and knowing after 35 years of reloading that the max load is almost NEVER the best load accuracy wise......I would concentrate more on finding the combination that most reloaders, most of the time use for a given combination, and start on the lower end of that neighborhood. It's taking a shortcut, but yes, I can see why folks might want to conserve resources. There are so many posts/pages/info with pet loads out in the wild, that just choosing a given max load, bumping a gain off, and going for it just doesn't make since as you will almost certainly miss your accuracy node and just beat your gun and your body. I'll give you a real world example. 44 Magnum with TiteGroup and a 240 Cast bullet. In the great range of published charges for that, it goes all the way up to 10 grains (or even more from some sources) of TiteGroup. Now, a 240 cast with 10 grains of TiteGroup...is miserable. Inaccurate, massive recoil, and a fireball that will scorch targets down range. It just sucks. But right around 7 to 7.5 grains, TiteGroup becomes magical, and makes for about the best target/fun/match shooting you can get with a 240 cast. Recoil approaches 44 SPL, and tack driving precision, at around 1100 fps. Nice for range day because you get 44 SPL recoil, without the ring in the cylinders, and it's still got enough oomph that you know you're shooting a 44 mag. Just my opinion.
     
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  3. jmr40

    jmr40 Member

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    Looking for pressure signs is not a good way to judge loads. None of the visible pressure signs show up until you're at about 70,000 psi. In other words by the time you see anything you're already in the danger zone.

    This is why I think even a cheap chronograph is a good idea for hand loading. If the books say 69 gr of powder is supposed to be giving you 3000 fps and you get 2900 fps with 68 gr then you're probably good to go with 68.5. If 68.5 is under 3000 fps then I'd go with 69 and as long as it is 3000 fps or less I'd call it good. You might well be getting 3100 fps at 69 gr and have an overpressure load that is still not showing any visible pressure signs.

    Every single one of my go-to loads have been borrowed from other shooters. I don't see any point in reinventing the wheel to get a good load. By looking around online or simply asking a question such as " What is a good load others are getting with H4350 powder and 165 gr bullets in 30-06". If a lot of people are getting good results with 56-58 gr of powder then chances are good I will find a great load somewhere between 56 and 58 gr too.

    I wouldn't blindly copy another's load. But once verifying it is a book load I'd start a little low and work up from there. There is still some experimenting to do, but it sure cuts down on the amount of time and components needed to find a good load.

    And I do find best accuracy at, or near max loads. I think it depends on the powder. I think it works best to fill the case so the powder has no room to shift in the case. With some powders a max load leaves some empty space in the case. Other powders that fill up the case with a max load tend to be more accurate in my experience.
     
  4. d31tc

    d31tc Member

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    Definitely using a chronograph. Not a labradar (must be nice), but I am monitoring velocity of every test shot. Seems to be in line with the published velocity. They are Barnes TTSX and the velocity for proper expansion is going to be the limit of my range, so I want to have an accurate number for what velocities I'm getting. Since the TTSX are dependent on higher velocities for proper expansion, if accuracy is a trade off for velocity, I will likely choose velocity and limit the range according to the range to the confidence level where I can get shots to hit my point of aim. I'm kind of starting over in a lot of ways and learning as I go (read my post about rings). Not the best of times, with limited components, to be starting over on working out the dope for my gun.
     
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  5. Thomasss

    Thomasss Member

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    It's kind of crazy, especially with Hodgden right now and they do seem to be changing the standards right now. The only true way to understand is to take a chronie and go test their published velocities. I did end up shooting .2 over max with powdered coat bullets just so my 9mm would recycle. Based on velocity I could go higher, but groups were nice and the gun recycled and there were no other signs of excessive pressure and that's all I want.
    On the other hand, I haven't loaded .357 mag for a long time. My 2012 IMR manual has 5.7 grains of PB for 158 grn. LSWC. Current Hodgden internet shown 4.9 for the same load. My chronie came out to show me 4.9 is within 35 fps on average of Hodgden's published velocity.
    Next question that I'm not sure how to answer is I used Win. Match primers and Hodgden was using Win. Magnum primers in their recipe.
     
    Last edited: Oct 26, 2021
  6. GeoDudeFlorida

    GeoDudeFlorida Member

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    Not very.
     
  7. mdi

    mdi Member

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    Agree with GeoDude above. Starting a load work up just one grain below max is not a good idea. Fortunately I don't have to deal with a shortage of components, and I like reloading (and my fingers) so I normally start well below max. I don't chase velocity numbers as I prefer accurate handloads that function well in my guns. (a good hit at 1100 fps is just as deadly as one at 1300 fps). I have sometimes started a work up at 10% below max, but that is my highest for a starting load and yes, a chrony is a good tool ( you can find a decent one for about $85.00. I used one of these until it took a hit from a 9mm 124 gr JHP going abour 1200 fps, dead center of the screen https://www.amazon.com/Caldwell-720001-Ballistic-Precision-Chronograph/dp/B00HTN5DTE/ref=sr_1_5?dchild=1&keywords=chronographs&qid=1635267399&qsid=146-8862055-6548407&sr=8-5&sres=B00HTN5DTE,B00HTN5290,B07FTJYQ9Z,B01B7OYNJG,B00VTZXF8Y,B00JZR1C10,B072JSP98J,B0823M5M6M,B086SW26DQ,B07Z467GZH,B082GP3M1D,B0008GGF9Q,B082Y3CD2F,B000S371TC,B07M8SC3KT,B0028MTBJ4,B08T5ZF5YZ,B001AI0NE4,B00WO9QT1O,B07FZLCD5Q)
     
  8. Howa 9700

    Howa 9700 Member

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    As a newb to metalica reloading myself, I've had the same questions. What I have recently come to realize is that the powder in my can is probably NOT the same powder that was used in the load data. For example, with LEE die sets, you generally get a LEE plastic dipper, suitable for that caliber. The LEE Reloading manual lists the weight in grains of various powders measured by those dippers. To verify process, I have actually weighed some of the powders I have using those dippers. One powder was dead on.....within 0.1 grains and close enough to chalk up to process. It was the only one. Out of 4 powders, 3 were off and one as much as a full 2 grains.

    What I've come to realize is that powders are not constant like say.....water. They are the result of formulas.....like baking a cake.....and can vary from one batch to another. Knowing that, the only thing that makes sense is to start at the bottom....or at least well off the top.....and work up.

    If really cramped for room........lack of components......I have also come to realize that every load I have started with went BANG.......and with rifles, all of them have fired at least 3 inch or better groups at 100 yards. Since I'm loading for hunting rifles for hunting use, any deer standing in front of any one of those loads when it went off was going to be in big trouble. Given time and components, I'd hope to do better, but any of it so far is a vast improvement over an empty box.
     
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  9. GeoDudeFlorida

    GeoDudeFlorida Member

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    Let me throw you a spitball ;)

    We all know the powder-maker is very familiar with their own powders... right? Sure!
    And, the bullet-maker is very familiar with their own bullets? Obviously.
    So which one tests bullet-case-primer-powder combos in a wide variety of guns these days?:thumbdown:

    The case and primer makers don't tend to publish reloading data - a few do who also make bullets - why?
    And just about every firearms maker says don't use reloads in their guns so obviously none of them publish loading data for their guns - except maybe for muzzle-loading black powder and maybe one or two cartridge black powder guns.

    So who's data is based on YOUR gun? And why should you trust any 50% of MAX and higher loads that aren't based on YOUR gun?

    Food for thought... :D
     
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  10. South Prairie Jim

    South Prairie Jim Member

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    I have never started at the highest listed charge, nor would I endorse that.
    With unfamiliar powder i run a one shot per charge pressure ladder with minimum once fired brass to establish the stopping point, such as heavy 'bolt lift' then work up an abbreviated ladder starting below that pressure point.
    I have not once used a chronograph to build a load.
    YMMV of course
     
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  11. Rule3

    Rule3 Member

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    Not really sure what your question is?
    Using your example of 69 grains we can "guess" it's a rifle load for hunting ammo. With slow rifle powders, 0.5 grain is not gonna make a whole lot of difference or at least any that a non bench rest shooter is gonna notice. Most rifle loads pretty much fill the case so a kaboom from just the powder is not likely to happen. If you shove the bullet in to deep than yes bad things can happen

    Now with small handgun cases and faster powder it will be something to worry about,

    Look at any reloading manual or website, the min and max loads

    How much difference in pressure is there? over a range of say 3 grains,

    https://shop.hodgdon.com/reloading-data-center
     
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  12. Herman B

    Herman B Member

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    Wow, verbose. No kabooms and not comfortable with the theoretical 'near max load start' approach. Doubt you'll find that approach recommended in a respected manual.

    So many seem to be chasing numbers vs reading manuals and tuning accuracy. Stay safe!
     
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  13. Blue68f100

    Blue68f100 Member

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    NONE at ALL.

    Dropping back 1gr off max on a 70gr charge is not at all. Depending on what range you are shooting it may take 100 rounds during a load workup to have something you can fully trust if you need to make a long range shot. Drop back 10% from max and make 1% steps to max. Some where in there you should find a node that you can work with. This is just the first step of many to getting a reliable load.
     
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  14. d31tc

    d31tc Member

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    Short and to the point.:thumbup:. If starting low, and up on charges, and velocity is a consideration what would be your recommended starting and stopping point be? I am not an expert, thus the reason I'm asking more questions than I am giving answers. Saving some powder and rounds, 5% lower than published max and work up vs. 10% lower? I have 21 bullets and would like to save 5 for hunting. I would also like to confirm ballistics out to 450, so groups at 200 (zero), 300, 400 and 450, with my final load selected. 3 shot groups and a load work up might not be in my cards this year.
     
  15. South Prairie Jim

    South Prairie Jim Member

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    This is a joke right ?
    A long range hunting load worked up in 16 shots ?
    Comonman.
     
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  16. Herman B

    Herman B Member

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    You are ill equipped to do any of that with 16 bullets. Totally unreasonable. Yet this is where some hunters conclude 'good enough'...go hunting, wound an animal...
    Even with perfect ammo, consistently hitting at 400 yds is not something that comes over a weekend of shooting.
    Methodical loading/shooting with ample supplies may eventually get you there.
     
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  17. GeoDudeFlorida

    GeoDudeFlorida Member

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    Buy commercial ammo this season and handload when you have the supplies to do it right.

    How can any of your questions be answered? We don't even know which cartridge, chambering, caliber, action, barrel, bullet or powder you're talking about. X+1 vs. X-1 grains of A-type powder in a Y-type cartridge case with Z -type projectile of R diameter loaded into D-type action... Say what? :scrutiny:

    Start at the beginning. Don't take shortcuts. Do it right according to what works. That's how you avoid ending up with a new nickname like "Stumpy" or "Ol' One Eye."
     
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  18. denton

    denton Member

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    There are two sfety issues to address with load workup: Are your powder charges below a plateau? Are your pressures safe?

    The third issue is whether you have found the most accurate load for your rifle.

    The first issue is addressed by chronographing perhaps 8-10 cartridges, made in identical pairs, in ~.5 grain increments, ending at the highest recommended charge. The point of this exercise is to see if MV advances in an orderly way as charge is increased. This is one of the major reasons for working up loads. It is not uncommon for loads to reach plateau, where MV does not advance as charge is increased. At any rate, as pointed out earlier, absence of pressure signs will reassure you that you are probably below 70 KPSI.

    The second issue is addressed by watching MV. If you are using the "book" load, and your MV is at or below "book" MV, adjusted for barrel length, you are almost surely below "book" pressure. Charge, powder speed, chamber geometry, leade, etc. all drive peak pressure and peak pressure is highly correlated with MV.

    Evaluating accuracy is tricky. Group size, standard deviation, etc. are measures of dispersion (variation), and measures of dispersion require more samples than most people suppose. They just don't behave as well as averages do. The average of three 5-shot groups will give you your long term average group size within about 25%. Getting more precision than that gets expensive in a hurry. Trying to compare group sizes with smaller samples creates a lot of room for error.

    Trying to gain lower group size by adjusting powder charge to within .1 grain is probably futile. With many powders, a 3 degree F change in barrel temperature is equivalent to a .1 grain change in charge. If you don't have a thermocouple over the chamber in your barrel, your variation will be governed by temperature, not powder charge.
     
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  19. Thomasss

    Thomasss Member

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    denton: Right on!!!! "Gee, I love that kind of talk!" Ensign Charles (Chuckie) Parker. McHales Navy. TV 1966.
     
  20. bullseye308

    bullseye308 Member

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    In my experience when loading anything, the most accurate load works out around 70-80% of max and with rifles there are usually 2 good accurate nodes, one around 75% and one around 90%. Hitting where you aim at will be much more beneficial than that extra .3” of expansion if you miss your expansion velocity for your particular bullet. Just my thoughts.
     
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  21. Telekinesis

    Telekinesis Member

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    First off, it’s your gun and your loads, so you’re the one who has to decide if the risk is worth the reward. That said, with a new load there’s no way I’d start off at or near max. 3 rounds, each at different powder weights, is not a good sample size to test for pressure.

    16 rounds is not enough to work up a load. It’s not even enough to find and confirm zeroes at your given ranges.

    IMHO this is a bit backwards. You’re looking at 2 variables - the bullet’s velocity window, and your personal/rifle effective accuracy window. Be honest with what positions you’ll be shooting in. If you’re a 1 MOA shooter from a bench and a 3 MOA shooter from field positions, 3 MOA is what you should be using. We don’t know your target size, but there’s the potential of getting a slower load to allow you to shoot farther just because of its inherent accuracy.

    For example, let’s take a max load that allows your bullet to expand at 500 yards, but the accuracy of that load means you can only take an ethical shot at 300 yards. Your max range for that load is 300 yards.

    Then say you have a slightly slower load that hits a node and is really accurate. It is slower, so your bullet will only fully expand at 400 yards, but because it is more accurate you can take an ethical shot at 400 yards. Your max range for the SLOWER load is 100 yards further than your max load.

    As mentioned, there are so many missing pieces of information that we can’t actually give you real numbers or know if the above example is relevant to your actual results (and these numbers are made up to illustrate a point).

    I’ll also say that if your bullet only performs correctly at a max charge, you need to reevaluate either your bullet choice, your cartridge choice, or your range expectations.
     
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  22. d31tc

    d31tc Member

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    Some background, I'm working on 100 rounds of 7mm RM using 150 gr TTSX under 63.4 gr H4831SC. I've switched scopes (and likely more importantly, base and rings) on the rifle, so trying to confirm what I had learned with these loads (that I worked up to based on 10%) rounds. I am now short on the 150gr rounds.

    Prior to that, I was shooting commercial ammo (150 gr Swift Scirocco) and probably have about 100 to 120 of those that I've fired out of this gun.

    As a contingency....prior to components disappearing, I got some 139gr LRX in case I could not obtain more 150 gr TTSX. Well, I couldn't find more 150 gr.

    I know I shoot more than the average person, but I also know I am not an expert. (Shot "expert":scrutiny: in the army, but that doesn't count for anything). But I also know what I've been hitting and the accuracy I had up until this year with the rounds I shot up until this year (going on about 180 to 200 rounds of 150 gr bullets out of this gun). I don't have a flinch...yet....:) so I still generally was hitting what I'm pointing at out to 400 given the right conditions (low wind).

    As I said, I was unable to find 150's this year, but but I have some 139gr that I can load under H4831SC. I guess I was thinking if I load enough to confirm what the ballistics are out to distance then I'd have some level of confidence needed to use them. If I don't, then I don't shoot. From what I'm reading here, my idea is a little whacked. Recommendation I'm hearing from people with more experience than me - Go back to the drawing board on the 139's. Sigh...fine...:( You all just want me to develop a flinch...:cuss:

    @South Prairie Jim Although I try to bring humor into my posts, on this one, I wasn't TRYING to be funny:uhoh:. Although it might sound funny, just not as in funny "ha, ha". Yes, 16 rounds training for distance would be a joke, I agree.
     
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  23. d31tc

    d31tc Member

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    Agreed, accuracy and velocity, the least common denominator determines the ethical range. When I was working up on the 150 gr TTSX my groups got smaller up to 62.4 gr H4831 (0.5 MOA 5 shot group) and then slightly larger at 63.4 gr (0.75 MOA 5 shot group) which of course could be shooter error. I selected 63.4 for the velocity and accuracy that works for me. There is a safety factor in there for velocity according to what Barnes says is required for full expansion. My shooting positions for hunting in this location is the same as my practice - prone, bi-pod, rear bag, with range finder and wind data. In fact, my shooting "bench" is my hunting blind.
     
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  24. Spare Parts

    Spare Parts Member

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    The question may presume a test method. Could we rephrase the question, "how does one use minimal components to work up a load?"

    The key is low standard deviation over the chrony. When working up a load, I remove as much variability (error) as possible. Powder and OAL is measured as precisely as possible. Perhaps even case volume and projectile weight is matched. Normally, this indicates serious obsessive-compulsive disorder, but there is a reason. If the chrony has a low standard deviation, then you're fairly sure of your position on the powder/velocity curve. There are (should be?) equations that map s.d. to confidence intervals, but that's beyond most reloading work. Suffice to say, n=3 with a sufficiently low s.d. can be good enough, especially if the objective is to not blow your face off.

    If the results tend to match the manufacturer's data, I have been known to skip a charge weight, especially a low weight one. Not much sense wasting components duplicating known data.

    Edit: some reloaders are looking for nodes - wide areas on the powder/velocity curve. In this case, the step size becomes 0.1 grain increments when exploring an interesting area. Just the same, reducing s.d. increases the confidence, which minimizes rounds downrange, which saves components.
     
  25. South Prairie Jim

    South Prairie Jim Member

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    Well you sure had me confused.
     
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