Powder dispenser deviation between charges

Jwjarrett

Jwjarrett

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Ok I'm still studying my reload manuals, so maybe there is an official answer for this. I've dropped and measured over 3 dozen powder charges. I'm aiming for 6.9 grains, which is the lightest end of the load data. After some adjustments, I got a 10 charge average of 6.91gr with the lowest being 6.81 and the highest being 7.02gr. Is there such thing as an acceptable amount of deviation?

Of course, I'm not talking match grade. I'm talking consistent results at the range that matches or exceeds factory range ammo.

40 S& W, BTW
 
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You don't say what powder or measure you're using. Some powders meter consistently, some don't and some measures are better than others.

1/10 is usually acceptable for general purpose ammo unless you're way out at the bleeding edge. Then you're in weigh every charge territory.

For reference, my ancient RCBS UniFlow gets a lot closer then a tenth with Accurate AA series powders. Blue Dot will fluctuate a tenth or even a little more.

For me, part of consistency is keeping the powder level in the measure up. I'll fill it, run it down maybe 1/3 and fill it again.

You're doing it right, taking time to test your setup.
 
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Your results will improve the more drops you make as your technique improves. You will get into a rhythm, tap at bottom, tap at top and you will see your results improve. I believe the common accepted variance, depending on powder is around .1 of a grain. Most scales will have that amount of variance also. That's why you tread carefully as you approach top loads until you have more experience.
 
As mentioned above, more info on powder and what measure you're using would help. Normal accepted variation of .1 (1/10th) grain for most powders. When I use Bullseye or TiteGroup I seldom see any variation from charge to charge. With Red Dot I will see .1 variation plus or minus.
Consistency is key when operating your powder measure, also make sure the powder level is kept at least 1/2 to 2/3 full in reservoir. So, if your target load is 6.9 grs; 6.8 - 7.0 would be an acceptable range. IMO :-)
 
I'm using a Lee Perfect Powder and Hodgdon Longshot. I was testing with just a minimum amount of powder. Tomorrow I'll fill the bottle and check again.

What trickler would you guys recommend?
 
When I first start, I find the measure is more consistent if I throw about ten "practice" charges and tap the hopper itself between throws. I don't load any of the throws, but dump them back in the hopper. If your hopper is a tall one, a baffle which keeps the weight of the tall column of powder off the cylinder helps too.
I'm with the other guys - a consistent +/- 0.1 grains is good enough, unless you're near the upper limit of safe charge or maybe benchrest, which I've never done. There are so many other variables; e.g., neck tension, crimp, case capacity, barrel heat, leading - that a tenth grain is pretty much moot for most shooting. Do watch out for a slow upward creep - I weigh one every ten to twenty throws to be sure my measure is stable. Historical experience with your measure and powder type will let you adjust that frequency as needed.
 
What are you using to measure 1/100 of a grain? 1/10gr is plenty accurate & no discernible diff can be seen in just 1/10gr with most powders & calibers. Even on max loads or bench rest, internal cae capacities can vary 3-4gr.
 
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One way to reduce any disparity in your charges is to maintain two or three powder measures. While it is initially expensive, if you've loaded for any length of time, you seem to accumulate them and good quality measures seem to last for a lifetime.

So for most revolver and pistol rounds (up to 12 to 14 grains): An old Redding with a small powder chamber. Even Unique measures well with this set up.

Mid size rifle (up to 35 some grains): An RCBS match rifle measure with a mid size chamber.

Larger rifle (up to magnums) an old Redding with the large rifle drum.

My Dillon loaders have both a pistol measure and a rifle measure to conform to what I'm loading on the press.

Using an appropriate measure you can measure very uniform charges of even the most recalcitrant powders like Unique, Blue Dot, SR 4759, etc.

As noted in the post above, you are probably better off weighing your cases and tossing the heaviest and the lightest ones out if you are shooting a very accurate rifle. While not necessary for standard loads, if you are a long range match shooter, it is more important than a slight variation in your powder charges.
 
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With a good powder measure, good technique, and perhaps a spherical powder IME you can expect most throws (80-90%) to vary +/-0.06gr from target . . . or from your average over a large number of throws. That's my experience using a Hornady measure, powders like H335 and W231/HP38.

Your extreme spread for 36 throws was 0.21gr, or for practical purposes +/-0.1gr. But you did not say how many charges were at the extremes. If only 2 were extreme, and all the rest were +/-0.06gr from your average, that would be very much in line with results I've seen. And that assumes that your scale is capable of repeatable measurements precise enough to tell you the truth.

Longshot is an irregularly shaped, flattened ball powder that I have no experience with. I would GUESS that results throwing that powder would not be as good as a with a pure spherical powder.

I've used a Lee Perfect measure when it was part or the AutoTrickler/AutoThrow attachment for the A&D FX120i, a high-quality scale. While most people would automatically assume the powder measure isn't very good simply because it's a "Lee", I didn't find anything really wrong with it except for occasional leaking. But I never measured its precision.

So you may not be too far away from "not bad". A powder change may tighten you up a little. And it's not impossible that a higher quality measure (Hornady and RCBS measures are pretty much identical) might help.

But you should look at what your target tells you when shooting from a rest. Using handguns with their short barrels and short range use, the powder variance may not make a visible difference.

To give you an idea of what it would take to get +/-0.02gr results . . . the price tag is close to $1,000. Many folks think that's crazy even for rifle reloading, and would say it's like using a 50 cal on chipmunks for handgun reloading.
 
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Most scales are not as accurate as your measurements. The average warrantee is +/- 2/10ths grain. I have 7 scales I use certified check weights to verify their accuracy.

I have a 30 year old Hornady scale that for some odd reason is well within a 1/40th of a grain. (1/4 of 1/10) When weighing long range rounds (308 Win., 300 Win. Mag., & 338 Lapua) I weigh every charge of extruded powder. I can see the that the powder granules are different sizes. Substituting larger or smaller granules can tune a charge as accurate as your instruments can measure! But the case, primer, and bullet all have a plus or minus. You can load 10 identical rounds (within you scale's tolerances) and the gun still may not shoot well! It could be you, it could be the gun, but very commonly some components don't like each other! (substitutes can make a huge difference!)

They only way to know what will happen with a new load combination is to take it to the range and shoot it. Your most accurate load to date is the standard you try to beat.

For rifles: different lot numbers of powder can change how accurate your gun shoots, but it is a small percent! (When IMR 8208XBR came out, the first and third batches of that powder were great, batch #2, not so much!) When starting out, I recommend you stay with time proven loads (Just because it is safe to shoot does not mean it will shoot well!) I went through 6 different powders before I found a good powder for 1000 yard 338 Lapua Mag! (ended up using H-1000! .25 MOA @ 1000 yards!: that is 2.5 inches!) If I miss, it's me! not the gun or ammo!) All the powders I tried were highly recommended, by powder companies and magazine writers! 2 fellow shooters helped out with their pet loads.

For revolvers: the alloy of the cast bullet or the alloy of the jacket will make a big difference. Also when switching from lead to jacketed or switching back; get the gun's riffling completely free of the other metal!

Ivan
 
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For tricky powders, Bluedot, Unique, Trailboss, etc, I’m in the habit of tapping the side of the throw each time prior to actuating the lever. I’ll also try to keep the powder volume at a similar level in the hopper. In my RCBS it does help.
 
I would suggest that you google Capability Study, 6 Sigma, and Standard Deviation. Dispensing powder is actually a Manufacturing Process that is quite easy to apply Statistics to. I have done capability studies on every single powder that I load with and knowing the Standard Deviation for each powder allows me to choose the powder and method for each application based on what I desire for that load. For example, Unique has a SD of 0.17 grains and using 6 Sigma this means the range of thrown charges will be +/- 3 Sigma (or +/- 3 times the SD). Since this means the deviation will be just a tick over +/- 1/2 grain I limit use for this powder to my 20 guage shotgun ammo because 1/2 grain in a 15 grain charge really isn't significant and in a 5 grain handgun charge it is significant.
 
fredj338 said:
What are you using to measure 1/100 of a grain? 1/10gr is plenty accurate & no discernible diff can be seen in just 1/10gr with most powders & calibers. Even on max loads or bench rest, internal cae capacities can vary 3-4gr.
Click to expand...

I have been measuring with the balance and a small digital. The digital and balance are spot on with each other to the 1/10. Of course the 1/100 is an estimate on the balance. I grew up on vernier calipers, so I read the scale similarly.
 
Jwjarrett said:
I'm using a Lee Perfect Powder and Hodgdon Longshot. I was testing with just a minimum amount of powder. Tomorrow I'll fill the bottle and check again.

What trickler would you guys recommend?
Click to expand...

You need to work on Consistency , consistent movements , forces , how the handle is operated , how hard the handle bumps the top and bottom stroke and most important ...is to keep the powder level at least 1/2 full ....put a mark on the hopper at halfway... when the powder level gets there , refill it ...
this helps greatly with consistent dropped weights .
Right now your way is giving you 0.21 grs. variances ....you want to get that down to 0.10 grs. variances between 10 charges.
When I got my first measure I just sat down and worked on my technique to get a perfectly consistent operation of the handle , the same movements and forces every time . That along with a minimum 1/2 full reservoir got me to 0.10 gr.
No magic about it , just develop a consistency of operation and practice .
Gary
 
With Bullseye +/- .1 gr works well. Time spent trying to get more precise than that is better spent on sorting cases and bullets.

One observation I've made - as a reloading session goes on, the powder tends to settle in the hopper and the weight of thrown charges tends to creep up a bit. It may be throwing .2 or so heavier than it was at the start. I'm wondering if a baffle in the hopper would help.
 
I have long subscribed to the concept of averaging the weight of 10 charges. Getting identical weights from each throw of a powder measure is nearly impossible due to the measure throwing a specific volume, not a specific weight of powder. If your target is 6.9 grains and your 10 charge average is 6.91, then you have arrived at 6.9 grains. A variation from charge to charge of +/-0.05 grains will not be noticeable unless maybe to a benchrest rifle shooter.
 
Nothing contributes to powder measure shot to shot consistency as much as a powder baffle.
NOTHING!
I have a RCBS standard measure and two Lees (1 disk, 1 drum).
With a baffle, they are all dead on for consistency.
 
I just goy back from a trip from Utah, where some of the guys are cerious about their shooting games.

You can put 2K out to get an elec. powder dumper and top it of with a trickler that gets to .004 for your loads past 1,000 yards.

However, most of us are happy with our under $200 scales, for our style of shooting.
 
FORGET the "average" method of 10 drops
It is meaningless. An average is just that an average. What if one drop was 6 and then one was 7 etc. The average is not what is in each case.The average would be 6.5 but one of those (6) would be an undercharge. If you do an average of 100 or 1,00 then you could have several that are way (weigh) off.


As mentioned weighing out to 1/100th of grain is also meaningless

Especially with a SLOW powder like Long shot. 6.9 or 7 or 7.1 you will not know the difference.

Don't get hung up on stats, SD and all that stuff.

Drop a powder charge weigh it, pour into a case, repeat untill you know what is going on. LOOK into each case to ensure the charge is in there.


Before someone with no actual experience(with it) whines about the LPPM. It is actually VERY accurate and doesn't leak(I tested it long ago with many powders and recorded ever drop. With stick powders it was better than my RCBS. Uniflow.
 
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