Accuracy in powder measure

[C5rider]

My brother is looking at getting a Lee Turret press and start reloading. I have a single-stage Lee. Powder goes from my measure, to my scale, then to the casing. With a turret or progressive press, once you've got the powder measure set up, there isn't a way to check each one, correct?

I find myself adding/subtracting just a little bit of powder on occasion. I was curious how much of a change in weight there might be if i didn't do that. I zero'd my Lee scale and added a "typical" amount of powder that I'd usually add. My TOTALLY un-scientific study revealed that the largest variance I've ever seen was 1/10th of a grain difference. And, that would have been an extreme (uncommon) situation.

If I hadn't checked them, would this variance be satisfactory? I don't go for max-loads so that's not an issue. I know there are a LOT of variables between powders and 1/10th-gr might barely be anything to some, but more of an issue with others.

For those guys loading thousands of rounds, how much of a variance is acceptible? Thanks for any insights!

 

[Steve C]

The larger the charge the less important small differences between throws will be. For example a 50gr load of IMR4064 that varies +/- 0.2grs will have little round to round variation. The same +/- 0.2grs in a 2.8gr target load of Bullseye will have a much greater affect on the ammunition's accuracy.

A lot of the uniform repeatability you get from a powder measure is determined by how consistently it is operated. It is always a good quality control to check the charge level to make sure the throws are consistent, though a small variation may be acceptable. When loading on a single stage I do a visual check to make sure the powder levels are the same and a scale check on anything that doesn't look the same. I also randomly check every 10th round or so. If the charge is off or showing poorer consistency than I can tolerate, I'll recharge all the cases and do what is necessary to obtain the consistency I want.

When using a progressive I check about every 10th charge after I've determined with a few more frequent checks that a consistent charge is being thrown.

I'm really checking for large divergence in charge throws, say .5 grs. A small variation of .1gr makes little difference, only about 10 fps on the few .45 acp loads I've checked on the chrono.

 

[Blue68f100]

Most all scales only have a ±0.1gr accuracy. Depending on powder type (large flake and tubular) you will get a lot of variations. If your not near max in most cases the std ±0.1gr variations is acceptable. Since I run a progressive I mainly only use Ball type powders because they give me them most consistent charges.

 

[john16443]

My brother is looking at getting a Lee Turret press and start reloading. I have a single-stage Lee. Powder goes from my measure, to my scale, then to the casing. With a turret or progressive press, once you've got the powder measure set up, there isn't a way to check each one, correct?

Not correct! It is just as easy to check the powder weight with the turret press as it is with a single stage press. The shell remains fixed in the shell holder, and the turret rotates above the shell. Once you drop the powder, it's simple to remove the case and check with the scale of your choice.

Your brother has 2 choices for the measures on the Lee turrets, strongly suggest he selecte the "Pro" auto measure. If you're going to be loading for pistol, it may also be worth getting the adjustable charge bar as this will allow you to better dial in the desired charge. That way you aren't limited by the hole sizes in the disks. My pro auto powder measure always dropped powder within +/- 0.05 grains using Bullseye, Titegroup, W231, WST, AA#2, AA#5, Clays, and HS-6.

 

[ATLDave]

My brother is looking at getting a Lee Turret press and start reloading. I have a single-stage Lee. Powder goes from my measure, to my scale, then to the casing. With a turret or progressive press, once you've got the powder measure set up, there isn't a way to check each one, correct?

Nope. You're free to remove the charged case and dump the powder to weigh it, then re-funnel it back into the case. Slightly faster, in my experience, and less likely to lead to spills, is to:
1. re-size and prime the case;
2. remove the case and zero a scale for the primed, empty case;
3. re-insert the case in the press and expand/charge;
4. remove the case and tare weigh the charge without dumping the case (this is why we zeroed the scale to account for everything but the powder in #2);
5. put the case back in the press, and load the bullet.

FWIW, when I first set up my Lee Classic turret, I do this tare charge weighing with the first 10 rounds at least, usually closer to 20. Then I'll back down to every other round for a while, if the powder is metering well and I have not had to re-throw ANY charges. If I've had to re-throw, then I just keep tare weighing every charge. Once I have confidence that a particular powder is metering well, then I'll drop back to this method for every 10th round or so.

But I also sort my brass by headstamp and know what the weight (and variation) is for that brass. For every round I produce, I weigh the finished cartridge. Between the variation of the brass and the bullet, this doesn't tell me if I've gotten exactly the right charge, but I can confirm that I haven't double-charged or no-charged a round. I have pulled a few because the overall weight seemed out of whack.

None of the above is conducive to fastest possible production, but I'm relatively new to reloading and am doing it more for the fun than to crank out thousands of rounds a week. Once I've been at it a long time, I may trust the process more completely, but right now I like having several QC steps built in.

 

[Cleftwynd]

ATLDave, QC is everything, it will prevent mishaps, some of which can be dangerous! Keep up the great work!

 

[ATLDave]

Cleftwynd, I do feel a strong desire to keep each and every one of my fingers, so I prefer to go slow, collect lots of data, and feel confident that I'm not building little pipe bombs or squibs.

 

[BYJO4]

Plus or minus .1 gr of powder is fine. A good powder measure will deliver this with no problem with the majority of the powder drops dead on.

 

[C5rider]

Thanks guys!

Good information.

 

[1SOW]

C5rider, (AF?) If you load with the smaller particle ball/small rod/small anything, you can expect much less than .1gr variances. The larger flake powders aren't as consistant.

When the hopper is first filled, it takes 6 or 8 trips around the turret press to "shake" the hopper and settle the powder for consistant drops. Do a drop, dump it back in the hopper, rotate the press around using the handle, repeat. After that, then measure a few drops (rotating the turret around with the handle) and measure for consistancy. When they come out the same, your ready to load.

 

[GLOOB]

Factory ammo has variance, too. Your targets should tell you what's acceptable or not.

 

[GLOOB]

When the hopper is first filled, it takes 6 or 8 trips around the turret press to "shake" the hopper and settle the powder for consistant drops.

I haven't found this to be the case with my hopper and powders. I've measured and measured, and there's no difference. I don't even throw the first charge back in the hopper, anymore.

 

[C5rider]

I have the Lee Classic kit's powder measure and I have noted occasions when the powder got low that I needed to put a little more powder on the scale to balance it out. Then I'd add a little more powder to the measure bin and it would bring the measured charge back up. Typically found this with Universal, which is my main powder that I use, due to its "universality". (Didn't see THAT one coming did ya?)

I could see where different powder shapes could act differently or be more sensitive to weight/settling.

 

[bdejong11129]

Since you asked about us that load 1000 rounds or more at a time. I have been in the simple habit of keeping any eye on the press.
I keep the power hopper above 25% full.
I check the throw before each loading session.
I check one every 200 or so and I always check the last one.
I trust my process and my equipment.

My son and I go through about 1200 or so rounds each month in IDPA, practice, and fun shooting so I have found it necessary to use several progressive presses so I am not loading all the time. I use lee equipment and the pro powder measure and it has served me well.

The only occasion where it did not drop was when the return chain was adjusted wrong on a friends press. This caused it to not return and reload. Other then that I am not a bullseye or long range rifle shooter so a tenth of a grain here or there is not going to be the cause for my poor shooting.

I use a single powder for all my loads which has greatly simplified my setups. I also use a dedicated press for all the calibers. With the cost of the pro 1000 and load master presses this is money well spent.



Disclaimer-this is my opinion and yours may vary.

 

[Lost Sheep]

My brother is looking at getting a Lee Turret press and start reloading. I have a single-stage Lee. Powder goes from my measure, to my scale, then to the casing. With a turret or progressive press, once you've got the powder measure set up, there isn't a way to check each one, correct?

I find myself adding/subtracting just a little bit of powder on occasion. I was curious how much of a change in weight there might be if i didn't do that. I zero'd my Lee scale and added a "typical" amount of powder that I'd usually add. My TOTALLY un-scientific study revealed that the largest variance I've ever seen was 1/10th of a grain difference. And, that would have been an extreme (uncommon) situation.

If I hadn't checked them, would this variance be satisfactory? I don't go for max-loads so that's not an issue. I know there are a LOT of variables between powders and 1/10th-gr might barely be anything to some, but more of an issue with others.

For those guys loading thousands of rounds, how much of a variance is acceptible? Thanks for any insights!

There is a way, even on the turret using auto-indexing.

After the powder drop, pull the case, dump the powder into the scale. Adjust weight if necessary/desired, refill the case and reinsert the case into the press. Then continue the interrupted cycle.

Better Alternative:

remove the powder measure and replace it with the original collar that came on the die and stick the Lee funnel into the collar. When the case is raised into the powder-through die, measure out your powder charge and dump it into the funnel. (Voila: you have just become a human powder measure.)

Note that some people believe that the VOLUME of powder is more significant than the WEIGHT. They claim that powder charges meted by volume, without regard to weight will produce tighter groups than powder charges meted by weight. They have considerable empirical evidence to support that claim. This evidence is mostly from long-range benchrest rifle shooting and generates considerable controversy/argument when brought up, so, make your own decision. I just thought I would point it out along with the fact that all mass-produced factory ammunition you buy is meted volumetrically. Buy a box of factory ammo, pull the bullets and measure the powder. Are the weights all the same? (If you do this, please let us know the results. I have never felt the need.)

The loading manuals give powder charges by weight as a matter of convenience and convention. Scientific laboratories communicate quantities of solids by weight. (Settling can change volume considerably.) Settling is not a major factor for (re)loading ammunition if the technique is consistent (powder drop height, amount of vibration during the loading, grain size uniformity, etc).

If you are pushing the limits of pressure, weighing each charge is probably prudent. But if you want the best of both worlds, don't trickle up. If you get an off-weight powder charge, toss the powder into another container (for later use) and drop another volume-meted charge.

Lost Sheep

P.S. Let your brother know that the Lee Classic Turret is far superior to the the Lee Deluxe Turret. Do not overlook Kempf's Gun Shop online or FSReloading. Sue Kempf is VERY knowledgeable and helpful.

The Lee Scale is very accurate, but if you are not familiar with use of a vernier, more challenging to use than the far more expensive, but user friendly Ohaus scales (sold by almost every other equipment maker, but under their own labels).