scffacenter1 Posted February 19, 2016 Share Posted February 19, 2016 I've been burning through a 8lb jug of alliant promo that i purchased last year, but it does not meter consistently at all so I am measuring each load by hand (i load on a single stage press anyway, so it does not slow me down too much) and while loading tonight I got to thinking about expected powder consistency out of a powder measure. I am loading to exactly 3.2 grains by my digital scale so I could technically be getting anywhere from 3.15 grains up to 3.24 grains which is one full grain of deviation. How accurate is acceptable from a powder measure with a powder that measures well? If a powder has a steep pressure curve (like the promo does) could it affect grouping more than a powder with a less steep curve? I'm sure at the amounts we are dealing with and the distances that we are shooting, the actual effect is probably very minimal but at what point (i.e. deviation) do you avoid a powder all-together in a powder measure. Link to comment Share on other sites More sharing options...
Absocold Posted February 19, 2016 Share Posted February 19, 2016 .09 grains difference (less than a tenth of a grain) for that charge is less than 4% deviation. Not enough to matter for anything except long range bullseye shooting. If a powder will throw within +- .05 grain on either side of my desired weight on any size charge up to 8 grains, I call it good and start cranking the handle. Greater differences and I make a judgement call based on how hot the load is (the hotter the load then the less variance I'll accept) and how much accuracy I need. After trying all of the powder measures that can be easily mounted to a progressive press, all my machines are sporting Lee Auto-Disks (not the Pro) with adjustable charge bars. Hornady's rotary was good but hates stick powder. Dillon's is accurate but fussy to maintain. Same story for everything else I tried, either not consistent or a pain to use. The cheap Lee just works and works. If your thrower is having issues handling the powder, you might investigate if you can fix it. Polish the funnel and drop tube. Use anti-static spray or rub dryer sheets on all surfaces that encounter powder. Make sure your press is grounded. Use the same motion and force every time you work the handle. Don't let the volume of powder in the hopper get too low (or too high for some of those really tall ones). Link to comment Share on other sites More sharing options...
jmorris Posted February 19, 2016 Share Posted February 19, 2016 I am loading to exactly 3.2 grains by my digital scale so I could technically be getting anywhere from 3.15 grains up to 3.24 grains which is one full grain of deviation. As fast as promo is not like your shooting benchrest with it but there are folks that say two tenths or even more doesn't matter it the firearm shoots better with a given powder. FWIW you can take a decades old scale and make it repeat charge weights within a kernel of powder. https://www.youtube.com/watch?v=nA0_KDjbBGQ Link to comment Share on other sites More sharing options...
Kosh75287 Posted February 19, 2016 Share Posted February 19, 2016 I compared rounds with Promo (I, too, am whittling down an 8# jug!) that I made with hand-trickled & weighed charges, powder-scooped charges, and charges thrown by a powder measure. The load was 4.0/Promo/230 LRN. I couldn't tell any difference between them, and neither could two other shooters. You can check your actual charge weight from a powder measure by throwing ten charges, weighing them and divide by ten. I'D wager that if the weight of 10 charges is 31.7 gr. - 32.3 gr., your ammo won't be the weak link in the accuracy chain. Link to comment Share on other sites More sharing options...
Hi-Power Jack Posted February 19, 2016 Share Posted February 19, 2016 Alliant Promo does not meter consistently. How accurate is acceptable from a powder measure? Your best way of determining "acceptable" metering is the size of your groups ... Fire 12 - 15 shots, from a solid support, at 20 or 25 yards - drop the 3-4 "flyers" and measure your group. My guess is that if you compared your hand weighed charges to charges thrown from a powder dispenser, you wouldn't see any real difference. What caliber, and what gun are you using? Link to comment Share on other sites More sharing options...
9x45 Posted February 20, 2016 Share Posted February 20, 2016 For Dillon machines, it depends on the powder. Corn sugar powders, like BE-86, will throw less than +/- .05 grains all day long, but corn flake powders, like Unique, not so good, more like +/- .15 grains. For action pistol at 3-15 yards, it hardly matters. Link to comment Share on other sites More sharing options...
GrumpyOne Posted February 20, 2016 Share Posted February 20, 2016 For Dillon machines, it depends on the powder. Corn sugar powders, like BE-86, will throw less than +/- .05 grains all day long, but corn flake powders, like Unique, not so good, more like +/- .15 grains. For action pistol at 3-15 yards, it hardly matters. I agree. Link to comment Share on other sites More sharing options...
scffacenter1 Posted February 20, 2016 Author Share Posted February 20, 2016 I'm shooting a glock. My powder measure is a hornady and throws the fifteen other powders I have great, but with promo it varies by up to a grain (.5 in either direction) and the felt difference between a 3.0 and 4.0 charge is more than noticeable. I don't do the ten throw average for this very reason. I will throw ten throws and measure each of them to see the extremes. I might pick up another measure to see if that helps, but I'm over half way through this 8# jug so the end is within sight. Link to comment Share on other sites More sharing options...
peterthefish Posted February 20, 2016 Share Posted February 20, 2016 (edited) If your Hornady measure came with a baffle, try taking it out and see if that improves metering. I found removing it helped with some fluffier powders like TrailBoss. Edited February 20, 2016 by peterthefish Link to comment Share on other sites More sharing options...
scffacenter1 Posted February 20, 2016 Author Share Posted February 20, 2016 Thanks, I'll give that a shot Link to comment Share on other sites More sharing options...
Hi-Power Jack Posted February 20, 2016 Share Posted February 20, 2016 My hornady throws promo up to a grain (.5 in either direction) One other potential source of error is your powder scale ... When you try to measure 3.5 grains of powder, your scale might show that as a range also - probably not on the order of +/- 0.5. but a part of that just might be scale error. I'd load 20 rounds with the Promo powder, and shoot them real slowly, over a solid rest at 20 -25 yards and see what the range of accuracy looks like compared to another powder or the Promo individually metered. Link to comment Share on other sites More sharing options...
scffacenter1 Posted February 21, 2016 Author Share Posted February 21, 2016 Well I did some messing around today, I brought out two other scales to confirm that my primary one was accurate. Before removing the baffle in my powder measure i was getting a spread of .8 grains over 50 throws. After removing it, i'm now getting a spread of .2 grains which i tested and groups are shooting just fine. Thanks everyone for the help. I don't know why this made any difference, but it definitely did. Link to comment Share on other sites More sharing options...
Hi-Power Jack Posted February 21, 2016 Share Posted February 21, 2016 Link to comment Share on other sites More sharing options...
peterthefish Posted February 21, 2016 Share Posted February 21, 2016 (edited) Well I did some messing around today, I brought out two other scales to confirm that my primary one was accurate. Before removing the baffle in my powder measure i was getting a spread of .8 grains over 50 throws. After removing it, i'm now getting a spread of .2 grains which i tested and groups are shooting just fine. Thanks everyone for the help. I don't know why this made any difference, but it definitely did.Glad to hear it helped. I get some flak from the mods around here for not contributing or something like that - nice to have a counterpoint I can refer to. Edited February 21, 2016 by peterthefish Link to comment Share on other sites More sharing options...
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