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Posted: 12/8/2012 10:27:27 AM EDT
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I am new to reloading and have reached the point of measuring out powder charges for 9mm and 45ACP. I started messing around with my RCBS 505 beam scale and thought to myself how accurate is this beam scale? (RCBS indicates +/- 0.1grains) Then I looked around at other measuring devices online then asked myself why don't I use an electronic consumer grade reloading scale that comes with a calibrated weight to ensure accuracy? (when I started looking into electronic scales most reloading weight scales have the same +/-0.1 grain accuracy) The question that I am at now, what is the difference in accuracy between my beam scale vs a reloading electronic scale?
To help understand my problem I weighed (10) 9mm, 115 grain bullets and (10) 45ACP, 185 grain bullets on my beam scale. Out of the (10) bullets weighed, I picked three bullets that measured 114.9, 115.0, 115.1, 184.9, 185.0 and 185.1 grains on my beam scale. I then weighed these same six bullets on a yearly calibrated electronic scale for comparison. The two measurements indicate my beam scale was measuring 0.149 to 0.243grains higher. (as opposed to 0.1grain steps I was making on my beam scale) This is based upon true 114.900, 115.000 and 115.100grain weights. (the calibrated electronic scale could measure to three significant digits in grams) I am curious to know at what point does weight measurement accuracy become unnoticable (or important) to the shooter? For instance if I measure a Bullseye powder charge of 4.5grains for my 9mm 115 grain bullet, it appears my accuracy will be at the level of 4.5grains, at most, +/-0.3grains on my beam scale. I don't have a reloading electronic scale to compare to a yearly calibrated laboratory scale for measuring powder charges. I want to understand how much my beam scale variability would affect weights I denote for load development of powder charges for various rounds. Thoughts? |
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I personally dont think it mattrs as much as most... Because the true measure is rate of combustion which is going to be controlled by surface area and displacement of the powder in the case. You could have 2 charges that weigh the same but burn quite differently.
I use an electronic scale, get it to the load i want and then dont sweat the small variations. My ammo shhots great for me.... |
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This is highly dependent on the charge in question. Different loads inthe same rifle with the same projectile will differ in their sensitivity to variations in powder load. In other words, at a load of 33.5 grains of 4064 under an 80 grain bullet in my 243, I get decent accuracy. A ±0.2 grain variation in powder charge at this load produces about ±40 fps variation in muzzle velocity in my rifle. My pet load (very accurate) for this bullet is 34.6 grains of 4064, where a ±0.2 grain variation doesn't cause enough spread in muzzle velocity for me to be able to measure it. In my .30-06, ±0.2 grains of powder weight makes not a shade of a difference as far as I've measured. In my 45, however, such a variation will make a big difference.
ETA: If you're worried that powder charge variation is causing you problems, there are several different methods for finding a loadout where the load becomes less sensitive. I don't want to derail your thread, but load testing is a way to measure what you're hoping to find out. |
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I don't even weigh my .45 charges. I weigh charges to set the volumetric powder measurement on the hopper and then I only throw and weigh a charge every 20 rounds just to make sure it hasn't moved on me. For my highpower competition loads, I throw a light load then hand trickle up to the exact weight on a beam scale for every round.
The scale doesn't need to be spot on, as long as it's consistent. That's if you're working up loads properly and not just getting a max load out of a book and jumping right to it. You should be starting pretty well below max pressure and incrementally increasing until you hit the combination your gun likes and the cases don't show signs of overpressurization. Then, whatever your scale reading was for that load, is what you continue to use...on that scale. Always work up your loads. |
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I don't quite follow your post.
Can you post up the 505 weights, and then the calibrated scale weights, side by side? It sounds like your 505 could be giving higher than actual weights, but I don't see how it follows that it is really +/- .3 grains as opposed to +/- .1. |
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I don't know what kind of electronic scale you have there, but I trust my 5-0-5, which is calibrated every time I use, more than the electronic scale which is calibrated once a year. Instead of using bullets as check weights, which by the way is a bad idea, get a real set of check weights, and compare that against your 5-0-5. If it's truly defective, then RCBS would repair/replace it for free.
GlockMonk |
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I adjust my powder measure and throw ten charges on the scale when setting it up for pistol ammo. 4.5 grains would weigh 45 grains for ten charges. I'm looking for an average throw weight and adjusting the measure to reach that goal.
Small charges of pistol powder do not need to be weighed individually. The ten throw method works fine and is more effective when setting up a powder measure. Use of a scale should be done the same way each time. I have check weights and I always use them to confirm my final setting. I also push the pan down slightly and let it rock to the final measurement settling on its own. |
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To answer your question up front.... Most reloaders don't worry about 2 or 3 tenths of a grain when loading HANDGUN ammo. Some rifle shooters / benchrest shooters do.... some get right down to classifying match grade bullet weights ( by 1 or 2 tenths ), weighing brass etc... I'm " old fashioned " and use a balance beam scale. I level both the x and y axis - before I zero the scale. This gives more consistent accuracy on charges. It also helps if you keep the pivot point clean / lubed. |
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Quoted:
To answer your question up front.... Most reloaders don't worry about 2 or 3 tenths of a grain when loading HANDGUN ammo. Some rifle shooters / benchrest shooters do.... some get right down to classifying match grade bullet weights ( by 1 or 2 tenths ), weighing brass etc... I'm " old fashioned " and use a balance beam scale. I level both the x and y axis - before I zero the scale. This gives more consistent accuracy on charges. It also helps if you keep the pivot point clean / lubed. Hangun ammunition requires precision charge weights, too. I load one cartridge that uses only 2.5 grains, and the permissible load range is very narrow. You'll find the same thing with H110 in large handgun cases, too., with an extra restriction on the weight of the minimum charge. A measure that's working correctly with a hand that has developed a consistent technique throws uniform charges that do not have to be weighed on every throw. The catch is how the weight changes with the level of powder in the reservoir, so baffles are not just recommended, but required in my opinion. The wierdest part of powder level in a reservoir is the unpredictable way the thrown weight will change. As the level drops, the weight might go up or down, and then after it drops farther, shift in the opposite direction. A funnel set in the reservoir top is a great way to control charge weight uniformity, used in conjunction with a baffle in the bottom of the reservoir. I also like the funnel shape of the bottle adapter sold by Sinclair. |
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Here's what I measured during my small experiment:
9mm 115 grain bullet #1 Beam Scale Measured=114.9grains, Electronic scale measured=115.141grains #2 Beam Scale Measured=115.0grains, Electronic scale measured=115.172grains #3 Beam Scale Measured=115.1grains, Electronic scale measured=115.249grains 45ACP 185 grain bullet #1 Beam Scale Measured=184.9grains, Electronic scale measured=185.127grains #2 Beam Scale Measured=185.0grains, Electronic scale measured=185.173grains #3 Beam Scale Measured=185.1grains, Electronic scale measured=185.343grains For clarification on the calibrated electronic scale used, it is a precision, laboratory based scale that is required to meet operating specifications. I appreciate the feedback so far. Since this is my initial effort into reloading it is hard to see from my perspective the impact of variability within powder charge weight measurements. |
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Quoted:
Quoted:
To answer your question up front.... Most reloaders don't worry about 2 or 3 tenths of a grain when loading HANDGUN ammo. Some rifle shooters / benchrest shooters do.... some get right down to classifying match grade bullet weights ( by 1 or 2 tenths ), weighing brass etc... I'm " old fashioned " and use a balance beam scale. I level both the x and y axis - before I zero the scale. This gives more consistent accuracy on charges. It also helps if you keep the pivot point clean / lubed. Hangun ammunition requires precision charge weights, too. I load one cartridge that uses only 2.5 grains, and the permissible load range is very narrow. You'll find the same thing with H110 in large handgun cases, too., with an extra restriction on the weight of the minimum charge. A measure that's working correctly with a hand that has developed a consistent technique throws uniform charges that do not have to be weighed on every throw. The catch is how the weight changes with the level of powder in the reservoir, so baffles are not just recommended, but required in my opinion. The wierdest part of powder level in a reservoir is the unpredictable way the thrown weight will change. As the level drops, the weight might go up or down, and then after it drops farther, shift in the opposite direction. A funnel set in the reservoir top is a great way to control charge weight uniformity, used in conjunction with a baffle in the bottom of the reservoir. I also like the funnel shape of the bottle adapter sold by Sinclair. I agree with you about requiring " precision charge weights " too... Heavy loads, and near max loads have to be precision charges. I should have been a little more specific about throwing range ammo charges - opposed to near max loads - especially with fast burning propellant, such as Bullseye. Someone that's on a single stage press, weighing each charge is much less likely to have a problem than someone that's cranking out pistol range ammo on a progressive press. A progress loader needs to stay within reasonable safety range - as the powder measure is going to fluctuate charges. In this case, a reloader would be much better off loading range ammo, and using a slower propellant, such as Unique. It allows a little more room for error ( NOT a double charge ). The only way to get " comfortable " with a powder measure is to persistently check those charges on the scale, and experiment with it. It measures volume - not by weight. |
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Quoted:
Here's what I measured during my small experiment: 9mm 115 grain bullet #1 Beam Scale Measured=114.9grains, Electronic scale measured=115.141grains #2 Beam Scale Measured=115.0grains, Electronic scale measured=115.172grains #3 Beam Scale Measured=115.1grains, Electronic scale measured=115.249grains 45ACP 185 grain bullet #1 Beam Scale Measured=184.9grains, Electronic scale measured=185.127grains #2 Beam Scale Measured=185.0grains, Electronic scale measured=185.173grains #3 Beam Scale Measured=185.1grains, Electronic scale measured=185.343grains For clarification on the calibrated electronic scale used, it is a precision, laboratory based scale that is required to meet operating specifications. I appreciate the feedback so far. Since this is my initial effort into reloading it is hard to see from my perspective the impact of variability within powder charge weight measurements. Which scale do you believe is correct? There are techniques ( bumping the table lightly ) to get a balance beam scale to " settle " correctly. It momentarily reduces friction on the pivot points. |
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+1 to what fundummy said.
There are techniques to make that beam scale read consistently. Especially, for the entry level 5-0-5 scale. The same applies for the manual powder measures, for example. You cannot just pull on the powder throw lever, and expect to get consistent charges every time. You must develop, and adhere to your own set of established protocols. GlockMonk |
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fundummy - I don't know which scale is correct. I am more inclined to trust the electronic scale that I used for my measurements. If I were to buy a calibrated weight set, to what degree is the weight listed for calibrated weights accurate?(would be a question I ask myself)
At some point I have to reconcile the variability of +/-0.1grains or as much as +/-0.2grains. I just don't see it now and I just don't know how this variability will appear down stream. I have read that burn rate, gun performance, shooting technique and maybe more factors will hide or reveal powder charge weight accuracy. |
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So let me get this straight...you've proven your scale is between 0.2 and 0.3 grains low for your loads and you're wondering what to do about it? Either factor that in or understand all of your loads will be a little low and you can buy a chronograph to test the speed of the bullet vs. charge weight. If all weights are off by 0.2 grains (can't measure farther than that on a505 scale) you will still have the same load weighed out every single time. Is the same as if you zeroed that you calibrated scale with something on it and zeroed it out. Now the scale will read light if you remove it but you can still factor the negative weight in to your calculations.
So unless you're a really elite awesome accurate shooter in wouldn't worry about the charge weights not matching your national certification. Unless you want to spend more money on a scale that is certified or you're so awesome at shooting that 0.2 grins of powder made a big difference I d go with what a chronograph says for velocity and compare that with your printed material. The 0.2 grains will be the same for every single charge you throw so it won't affect individual bullets. If it was off by 0.2 on some and 0.1 on others, sometimes heavy, sometimes light, it would be a problem. |
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Quoted:
fundummy - I don't know which scale is correct. I am more inclined to trust the electronic scale that I used for my measurements. If I were to buy a calibrated weight set, to what degree is the weight listed for calibrated weights accurate?(would be a question I ask myself) At some point I have to reconcile the variability of +/-0.1grains or as much as +/-0.2grains. I just don't see it now and I just don't know how this variability will appear down stream. I have read that burn rate, gun performance, shooting technique and maybe more factors will hide or reveal powder charge weight accuracy. Unless you have a load that is simply too hot with the addition of 0.2 grains of powder, you'll never see the difference on the target for a bottle neck cartridges from about .222 Rem cartridges and up in capacity. If you're that close, you are not shooting a robust load that can absorb the difference and the basic load needs to be adjusted anyway. A 0.2 grain change in a typical charge of say 25 grains in a .223 Rem case is less than 1%. The only way you'll see that on the target is with a rifle that is accurate enough to discriminate the difference, i.e., a full up custom gun, and brass with the full work up to perfect it to the degree possible. Benchrest shooters love to use Harrel measures; guess what, they'll throw short extruded powders like H322 or Reloder 15 to +/- 0.2 grains, just like a Uniflow that has been polished. They'll make overall changes to accomodate the ambient conditions, but you'll have to look hard to find a scale at a match. |
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