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Question about power measure consistency #14166161 09/30/19
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Remington725 Offline OP
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Curious what amount of variation you all consider acceptable when throwing powder charges? By acceptable I mean a variation that won't affect safety and accuracy significantly.

I have an RCBS measure and with some ball powders I get great consistency while some short stick type powders will throw plus/minus 0.5 grains, sometimes a little more. This on different magnum rifle charges of 65-80 grains.

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Re: Question about power measure consistency [Re: Remington725] #14166246 09/30/19
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mathman Offline
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Which short stick powders give you that much variation?


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Re: Question about power measure consistency [Re: Remington725] #14166293 09/30/19
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Originally Posted by Remington725
Curious what amount of variation you all consider acceptable when throwing powder charges? By acceptable I mean a variation that won't affect safety and accuracy significantly.

I have an RCBS measure and with some ball powders I get great consistency while some short stick type powders will throw plus/minus 0.5 grains, sometimes a little more. This on different magnum rifle charges of 65-80 grains.

I would run the measure differently if giving that much variation out of the RCBS. My dad taught me you can double-tap at the top or the bottom, or both, and get more consistent throws out of some powders, but he always preferred to throw the charge light and trickle in the last bit to get everything equal.

I have a several throwers: a Lee plastic one, two RCBS of different sizes, and a Redding. The Redding and the RCBS do better with ball, flattened ball, or super short stick powders. The Lee does better with bigger stick powders. I alter the way I throw charges depending on how well the powder is dispensing.


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Re: Question about power measure consistency [Re: Remington725] #14166549 09/30/19
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I've tested a few powder measures. Oddly, one of the best I've tested is the Lee Perfect Powder Measure.

On ball powders, the Hornady balance scale has an error standard deviation of about .04 grain. So 95% of the time, you can see changes as small as .08 grain.

With 2520 ball powder, the Perfect Powder Measure is better than that. I don't know how much better, because I can't measure changes that small.

With H4831SC, the Perfect Powder Measure has an error standard deviation of .1 grain. So 95% of your powder throws will be within plus or minus .2 grains.

The Hornady Lock N Load throwing H4831SC has an error standard deviation of .14 grains.

All of these are completely adequate unless you're shooting a 1/2 MOA gun at 1000 yards. Even then, the end result is still pretty good.


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Re: Question about power measure consistency [Re: denton] #14166574 09/30/19
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mathman Offline
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Denton,

Have you ever investigated using the central limit theorem at the loading bench? By this I mean for example comparing the statistics of thrown 60 grain charges to the statistics of 60 grain charges each being the aggregate of three nominal 20 grain throws.


"In the real world, think of the 6.5 Creedmoor as the modernized/standardized/optimized version of the 6.5x55/.260." John Barsness 2019
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Re: Question about power measure consistency [Re: Remington725] #14166609 09/30/19
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bsa1917hunter Offline
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Originally Posted by Remington725
Curious what amount of variation you all consider acceptable when throwing powder charges? By acceptable I mean a variation that won't affect safety and accuracy significantly.

I have an RCBS measure and with some ball powders I get great consistency while some short stick type powders will throw plus/minus 0.5 grains, sometimes a little more. This on different magnum rifle charges of 65-80 grains.


If it varies by more than .3 grains in a cartridge the size of the 30-06 , ill just drop low and trickle the rest in. On some of my 308 loads, i drop charges that are within a grain from one another. Sometimes ill pick a powder that gives me that type of consistency over a different powder. One reason i switched to ar comp in the 308, 6woa and .223.


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Re: Question about power measure consistency [Re: Remington725] #14166624 09/30/19
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My RCBS is right on with ball powder and .2/.3 with stick. I’ve learned to live with it.

Re: Question about power measure consistency [Re: Remington725] #14166677 09/30/19
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vapodog Offline
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I still have and use an old Herter's measure....it throws as accurately as any of the others I have.

Ball powders are always quite uniform and such powders as IMR 4320 which is a short stick powder works quite uniformly.....I always look for SSC or SC on the courser powders.....such as IMR 7828 and 4831

At the range, I've not noticed any difference in +/-.5 and none of the deer or elk I've shot have noticed.....so I set my powder measure to the norm and check weigh a dozen consecutive loads to insure that I'm hitting somewhere around the middle and load ammo.....this has not ever caused me a problem.

To your question....ball powders run about +/- .2 grains and the courser powders run about +/- .5 grains.....My favorite powder measure is the Hornady.....

Re: Question about power measure consistency [Re: Remington725] #14166756 09/30/19
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If you want a powder measure that is more consistent I would suggest trying a culver type powder measure like a Harrell’s.
Even a Harrell’s has its limitations, it will throw ball and stick powder better than a conventional such as RCBS,Redding,Lee and Lyman etc. but will not throw flake powder at all !!! When using HS6 I have to dig out the RCBS.

One thing I have to admit I have never tried is mathman’s Central Limit Theorem 🤔😬

Re: Question about power measure consistency [Re: Remington725] #14166902 09/30/19
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When using stick powders I don't rely on throwing charges. I throw charges about 0.5gn under and then trickle up with a powder trickler. I too have got irregular charges with the stick powders and it gets worse as the granules/logs get bigger (ADI 2209, 2213sc, 2217 and Re19 etc.). I've found if a log jams then if I apply a bit of force to cut it the charge goes up 0.2-0.3gn. If I back the handle back a bit and have another go then the powder settles a bit more and I get a higher charge. So I like to throw a lighter charge and trickle up. Then sometimes I throw a charge that is 0.7 gn under for some reason. I just done trust thrown charges with stick powders. I don't have one of those baffle thingies that is supposed to help the powder flow more consistently.

Winchester ball powders and some of the faster ADI powders (Benchmark 1 and 2) which have very small stick granules and flow just like ball powders I tend to rely on thrown charges but usually cut my charges 1/2 grain from max just to be sure. I've had my Hornady thrower for about 20 years now so the above comments are based on 20 years reloading experience. I also don't mind the extra time. I tend to treat handloading as a hobby (like tying flies) so the extra step of trickling powder doesn't worry me. I like to wait for a nice rainy day and then potter round in my loading room.

Bravo

Re: Question about power measure consistency [Re: Remington725] #14166937 09/30/19
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I have had several, most do quite well with large amounts of rifle powders, better will "Ball" powder. My issue is with Bullseye and small loads. my favorite load is 2.7g of Bullseye in a 38 special with a 148g HBWC. The only load my S&W Model 52 will accept. I have yet to find a powder measure/thrower that will do this consistently. Still load those by hand.

Re: Question about power measure consistency [Re: mathman] #14167040 09/30/19
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Remington725 Offline OP
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Originally Posted by mathman
Which short stick powders give you that much variation?


I should clarify that the absolute variation was about 0.5 grains. Plus/minus 0.25

Yesterday I noticed it with RL26 but have noticed it with IMR 7828 short cut. And also H1000 as I recall.

Has anyone tested groups sizes of thrown charges vs. individually weighed charges? And what level of variation starts to become statistically relevant.

Last edited by Remington725; 09/30/19.
Re: Question about power measure consistency [Re: Remington725] #14167098 09/30/19
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One can not prove consistent volume with a scale and you can't prove consistent weight with a graduated cylinder

Re: Question about power measure consistency [Re: Remington725] #14167112 09/30/19
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Originally Posted by Remington725
Originally Posted by mathman
Which short stick powders give you that much variation?


I should clarify that the absolute variation was about 0.5 grains. Plus/minus 0.25

Yesterday I noticed it with RL26 but have noticed it with IMR 7828 short cut. And also H1000 as I recall.

Has anyone tested groups sizes of thrown charges vs. individually weighed charges? And what level of variation starts to become statistically relevant.

No. I put together precise ammo. I have seen such variability using stick powders in measures that I check charges with a scale. If I don't weigh it, it could be off by a few grains, due to bridging in the measure, both on the minus side, and then with the next round, on the plus side. I don't want that. And if I am going to weigh charges, I will make them exact by adding or removing powder. Why would I build crap, that could be dangerous, when what I want is precision that I can rely on, no qualms or fears included? If 60 grains shot the best in my tests, then I will load 60 grains to shoot. If 60.3 grains happened to be what I tested, and it shot the best, I'd duplicate that. I generally don't use half-grain increments in load testing with cartridges holding more than 30 grains of powder, but I will still replicate what I have tested to the best of my abilities and equipment.

Maybe it's my personality, maybe my upbringing, but I don't have tolerance for errors that are easily managed with a small amount of extra effort. And in things like guns and vehicles, I don't believe in loose tolerances. Because I rely on those mechanisms with my life.


I belong on eroding granite, among the pines.
Re: Question about power measure consistency [Re: Remington725] #14167117 09/30/19
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Mule Deer Offline
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Remington,

Plus or minus .25 grain is insignficant in hunting loads for charges of that size--unless, of course, you're trying to shoot prairie dogs beyond 500 yards. That much variation will result in about 10-15 fps in velocity with loads in the 3000 fps range.


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Re: Question about power measure consistency [Re: Remington725] #14167131 09/30/19
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Swifty52 Offline
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Originally Posted by Remington725
Curious what amount of variation you all consider acceptable when throwing powder charges? By acceptable I mean a variation that won't affect safety and accuracy significantly.

I have an RCBS measure and with some ball powders I get great consistency while some short stick type powders will throw plus/minus 0.5 grains, sometimes a little more. This on different magnum rifle charges of 65-80 grains.


If you are using a uni-flow, put a baffle in it. Evens out the powder weight for a more consistent drop. 6-7 bucks does wonders for it.



Swifty
Re: Question about power measure consistency [Re: denton] #14167332 09/30/19
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Trystan Offline
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Originally Posted by denton
I've tested a few powder measures. Oddly, one of the best I've tested is the Lee Perfect Powder Measure.


With 2520 ball powder, the Perfect Powder Measure is better than that. I don't know how much better, because I can't measure changes that small.

With H4831SC, the Perfect Powder Measure has an error standard deviation of .1 grain. So 95% of your powder throws will be within plus or minus .2 grains.



I've had the same exact experience with my lee perfect powder measure as you Denton.

I've also had the same experience as the OP with the RCBS powder measure.

Apparently Mule Deer tested a Lee a few years back and his experience was different but I'm leaning toward they must have made some changes recently. I think there around $20 if I remember correctly


Trystan

Last edited by Trystan; 09/30/19.

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Re: Question about power measure consistency [Re: Remington725] #14167474 09/30/19
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I did an experiment some years back comparing velocity SD for charges produced by throwing using a Lee Perfect thrower vs those produced by trickling up on a scale. I don't have my notes in front of me, but I tried a few of the propellants I use the most - Varget, H4350, 296, and a couple of others IIRC - and I found that the velocities were at least as consistent for the thrown charges, if not more so. I've thrown all my charges since.

Re: Question about power measure consistency [Re: dan_oz] #14169831 10/01/19
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Originally Posted by dan_oz
I did an experiment some years back comparing velocity SD for charges produced by throwing using a Lee Perfect thrower vs those produced by trickling up on a scale. I don't have my notes in front of me, but I tried a few of the propellants I use the most - Varget, H4350, 296, and a couple of others IIRC - and I found that the velocities were at least as consistent for the thrown charges, if not more so. I've thrown all my charges since.


What dan said. I used a Redding #3BR. I could not see significant differences in accuracy, velocity or SD. I will have to look for powders used but H4831SC was for sure on the list, as well as IMR4064.


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Re: Question about power measure consistency [Re: dan_oz] #14169839 10/01/19
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Originally Posted by dan_oz
I did an experiment some years back comparing velocity SD for charges produced by throwing using a Lee Perfect thrower vs those produced by trickling up on a scale. I don't have my notes in front of me, but I tried a few of the propellants I use the most - Varget, H4350, 296, and a couple of others IIRC - and I found that the velocities were at least as consistent for the thrown charges, if not more so. I've thrown all my charges since.

YUP....this is totally believable

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