Need some advice

[Yankeetom]

I’m finding that my RCBS uniflow 3 is not holding the .1 (+/-) grain tolerance that is advertised. It’s varying around .4-.6 grains during a 50 round load. I check the weight every 10 throws and adjust accordingly. I only load pistol and just for range fun. I chronograph my rounds and think the numbers I see reflect the difference in throw weight from round to round. I’ve trickled a few different calibers and the fps numbers are much more consistent.
Now all I load are all accurate bullets for me and my guns as I’m only shooting 25 yards.
I’m a retired machinist and not being able to hold tolerances drives me nuts.
My questions are what is an acceptable weight difference in throw weights for just target shooting, I don’t mean starting and max numbers but it a recipe throw. Am I just being to anal chasing what I’m seeing for the sake of target shooting. I’m reading that Redding makes a very accurate low volume for “pistol “powder thrower, any opinions on it.
I load .45 acp, .38 special and .357 magnum. Powders I use are W231, W244, W296, Longshot and TrueBlue.
Also my scale is a good one that holds (+/-) .02 grains. Another question is on progressive presses what is the powder charge tolerance that is being banged out with every pull of the handle.
Thanks…Tom

 

[TXBryan]

Like you I check the throw weights against a digital or reliable balance scale every so many pulls of the handle or turns of the crank. Generally I'm pleased with how close things stay once I get everything adjusted properly.

I do not have a progressive but rather a Lee Turret and once things are "set" my every-so-often checks reveal tolerances close to one or two tenths of a grain with most powders. This depends, naturally, on which powder is being metered as some meter better than others particularly within certain weight ranges. I tend to check more frequently when beginning a batch and a little less once consistency is realized.

For rifle loads I use single stage presses, a Redding and a Lee, and a Lee Perfect Powder measure. My experience with the Perfect is that once set it varies virtually not at all checked against a good digital scale.

I don't pretend to know what tolerances may be acceptable because we are all likely to have a different opinion on that. I don't worry too much about a tenth grain, or even two tenths, for handgun target loads especially in larger volume use such as .44 Mag, .44 Special, .45 ACP, .45 Colt, .357, or even most .38 Special. When loading for .32 S&W, or even .32 S&W Long or .32-20, I tend to be a little more picky as variations tend to be a larger percentage of the whole.

It sounds like you are concerned about half grain variations and, frankly, I would be too. That can, and should be, fixed. That level of variation may, or may not, be hazardous but at the very least your handload accuracy probably won't be what you're looking for.

Bryan

 

[shil]

.4 to .6 grain variation is indeed a bit much. I'm sorry I'm not familiar with the Uniflow 3, but my 40-year-old Uniflow isn't that bad even with Unique, a notoriously poor-metering powder. If I load with Unique, I generally check every fifth round with my progressive (Hornady), every tenth with the Uniflow. If you are working your measure by hand, throw the handle firmly and see that it gives a good tap at the limit of each throw. If it's on a progressive, make sure the operating linkage of the press is working the measure to full throw. I hope I helped.

 

[Paul in Nevada]

You should be able to get closer than that with ball powders.
Adding a baffle helps. Some other tricks: keep the hopper about half full, tap the hopper gentle a few times to settle it, give the handle a tap-tap at both ends of the throw, throw about 10-20 charges before you try to dial in your charge weight, etc. They used to sell a small drum for light powder charges that would probably help but they are hard to find now.
Your other option is to throw light and trickle up.

 

[BB57]

Paul is spot on.

Consistency is key, to ensure consistent powder settling.

I do three taps at the bottom to both ensure nothing hangs in the cylinder and to promote consistent settling prior to the next change. I just do the one tap at the top.

I always use a baffle and I keep the measure between full and 3/4 full.

I run at least 10 charges before pulling one off to weigh.

I use a Redding BR 3 measure as well as a Hornady Lock and Load measure with small and large cylinders, and a half dozen Dillon measures with XL, L, S and XS charge bars. I use the smallest size that can still deliver the charge weight/volume needed to ensure I am always working with maximum column length and minimum surface area at the top.

For progressive presses, consistent operation is vital as anything that interrupts the cadence on the charge plate can interfere with the accuracy of the measure. If something goes wrong on the shell plate, I run 3-4 charges dumped back in the hopper before I start keeping them again.

The same thing goes after stopping for any length of time as the powder settles more in the measure and charges will be over weight until stasis again occurs in the powder density.

Solid mounting of the press on an immovable bench is also vital to consistent powder measure operation with any press mounted measure.

—-

I load precision .308 ammo on my Dillon 550B with a Whidden floating tool head and clamp kit, along with small base dies and a BR3 measure on a 3/4” powder measure adapter. I set the measure up to drop .1 gr low and trickle up the half or so to,es that is needed as it does drop +/- 0.1 gr, even with strudel powders.

When loading precision .223 with ball powders, I check the weight but don’t trickle up. At those 25 ish grain charge weights it drops close enough with about a .1 gr total range.

In both cases run out of the completed cartridge is around .001” and I fix or reject anything over .0015”.

 

[Duckford]

Safety tolerance can be seen more from a cartridge to cartridge basis. Medium pressure 38 Special in a 357 Magnum handgun? Depending on your powder, you may have vast tolerance for safety, both low and high. 0.5 grains +/-, IF CONSISTENTLY IN THIS RANGE WITH NO ODDBALLS, might be considered safe, if not desirable.

Strong near max loads for a K frame magnum? Maybe you should just stick with the balance beam and keep weighing them for safety. Powder puff light loads? You may have a lot of safety margin for hotter loads thrown by the powder dispenser, but what is your tolerance to prevent squibs or malfunctions in auto loaders? How sensitive is the powder? Is it the kind that works well all across its loading band, is it something that gets "hot" quickly like Bullseye as the powder charges increase?

I think the bigger question is "if there is a reason for high inconsistency, will that physical problem cause oddball charges outside the normal broad range of powder charges thrown that could cause serious harm" is the bigger one. A powder thrower that stays within 0.2 grains +/- can be relied upon, but if something is giving a broad range for any reason, the risk of radically different powder charges and oddballs increases, because the band change is happening for a reason, and the powder/thrower problem causing it could very well give you one outside of the -0.5 grain +/-.

For safety sake, if you question it, maybe don't use that powder with the thrower without weighing every charge. Change your thrower, change the powder, or weigh it. Better safe than sorry? If you don't trust it, go with that. Weighing charges is much more fun then spending time piecing together a damaged weapon.

When I've progressively loaded handgun with my RCBS ProChucker 7 or whatever they call it (pure trash is what it really is) the one thing that actually worked was the powder thrower. I had an empty spot in the rotating line to spot check powder on occasion, never had more than .2 grains off, so I trusted it enough to do my work.

As for rifle, I just throw the powder charge and weigh every single last one on the beam. The powder weight thrown is inconsistent, and when it comes to rifle work I prefer high consistency, and nothing beats the beam. So, even if it was throwing powder weights in a safe range, I would not just throw and go.

 

[TIMETRIPPER]

Tapping is good. To see how it helps, throw a charge onto a dish then set it down below the measure and tap a few times. You may be surprised at how many powder granules drop down when the measure is tapped.

John

 

[venomballistics]

Given the case details, ball powder and a relatively small cartridges involved, I think the powder measure is whacked.
I retired my LEE imperfect measure for less variance in a larger volume cartridge

 

[22hipower]

This won't help with your Uniflow 3 issue, but for years I was not confident of the weights thrown by my powder measure; close enough probably. . . . Maybe 15 years ago I bought a RCBS Chargemaster and now weigh every load, pistol and rifle. Might take a little longer, but not much, and I know every load has 1/10 of a grain or less variation. Might not be practical if loading thousands of rounds but works fine for me loading a box or two at a time.

As to variation in velocity when chronographing loads, you're going to get some variation no matter how consistent the powder load. At least I do.

Jeff
SWCA #1457

 

[Eddietruett]

On my Lee press I switched to the disc measure. It is surprisingly consistent. It varies a tenth or two but for light Target loads that’s not a problem. Certainly not enough to vary accuracy 25 yards and closer. It’s also much quicker to set up changing calibers. With the exception of Unique, my Dillon stays where I set it for hundreds of rounds.

 

[SMSgt]

My 45-year-old Herter's powder dropper is very consistent with the powders you mentioned. Longer stick powders for rifles are more of a problem, but I drop low and trickle up as needed.

 

[rwsmith]

Did you......

Did you put a baffle in the powder hopper??? That increased my throws to about .2 grain variation (max). I still check the loads with a digital scale often because even though I'm very consistent with the operation. Up (bang) halfway down, up to the top again (bang) down to throw powder. Some powders simply don't throw as well as others.

I can throw a long string of perfect loads but then one will be off. That's why I check them.

Oh, I have another technique. I tare the case and throw the load. I put the loaded cartridge back on the scale and check the difference. If it's off by a few tenths of a grain, I add or subtract powder. If it's way off, I just dump it back in the hopper and try again.

 

[GypsmJim]

Every measure has a variance. If you are "adjusting" every 10 throws, you are doubling that variance.

 

[243winxb]

Old unit- For pistol, the small unit would be used.
Powder Charge Thrown:
Small: .5 to 50 grains of Ball, Flake or Extruded powder
Large: 5-110 Grains of Ball, Flake or Extruded Powder

New current model- New on the UPM-III is the ability to use one metering cylinder and rotor for both rifle and pistol to throw charges from 0.5 grains to 95 grains.

A "small" powder throw may be more accurare?


Needs cleaning? RCBS® FAQ: Disassemble and Clean RCBS Uniflow™ Powder Measure - YouTube

 

[243winxb]

Add a baffle #90225 RCBS Powder Baffle | RCBS

Looks like 3 different ones?

As said, ball powders should measure a lot closer then stick powders.

Check scale with test/check weights.

 

[STORMINORMAN]

One can probably better a ".4-.6 grain" variance with the LEE dippers...?

One possible solution would be to drop into a scale pan and trickle (as needed) to the desired weight.

Cheers!

P.S. Although most progressive press users have some kind of "powder cop" to detect missed or multiple charges, one still needs to verify the accuracy & reliability of the drop: I would opine that +/- .1 gr is the usual goal...?

 

[M29since14]

For blaster-grade pistol or rifle ammo, +/- 0.1 grains should be plenty good enough for all but the smallest cartridges. Getting there is pretty simple with ball powders, but with extruded rifle powders the only success I’ve ever had is to weigh each charge.

I have read that some benchrest shooters have sophisticated measures and don’t weigh charges. I suppose that is logical, for shooting at 100 yards or so. I don’t know. I’ve been weighing for a long time and don’t see much likelihood of change.

The automated electronic trickler I have (I think it is a Hornady) seems to get a charge with most extruded rifle powders usually within -0.1 to +0.2 grains. That’s not good enough for me, so I check the charge on a different scale that I “believe” () is likely more accurate and adjust it accordingly.

You can really make yourself miserable with this stuff. Same with runout of loaded ammunition. That’s been my method I’ve developed over more than fifty-years of handloading. I may get smarter someday…

 

[Hasbeen1945]

I have found this method works for me. I have a Harrels measure mounted above my digital scale. I drop directly into the scale pan.
On the right side of the scale I have a loading block with primed and belled brass. On the left side is charged brass. I still do visual check after loading.

 

[BB57]

Every measure has a variance. If you are "adjusting" every 10 throws, you are doubling that variance.

Agreed. When I set my powder measure, I throw 10 charges directly back in the hopper and then throw the next 10 on the scale and divide the total weight by 10 to get the average.

For example if I am setting the measure to throw 8.5 grains of powder, and the weight for 10 charges is 83.5 grains, I’ll adjust the measure to throw a slightly higher charge weight and repeat until I get 10 sequential charges that weigh a total of 85 grains plus or minus a couple 10ths and then repeat it to ensure I get 85 grains again within the same narrow range.

It take a little longer but I know the measure is throwing the desired charge on average within a reasonably tight tolerance. I am not left chasing my tail sampling random charges that might individually be +/- 1-2 SD from the mean and cause me to doubt the setting of the measure due to normal charge to charge variation.

 

[Nevada Ed]

I always hit my powder tube with the bottom of my fist, 3-4 times to settle the powder.
Then I unload 4 dumps, before I even start to weigh charges.

You can see the powder "Settle" and the starting drops , with at least 1 tap;
at the top & bottom stroke, will let "static" powder drop with the rest of the powder volume, hopefully.

.4-.6 difference is not a good thing with ball powders;
you need to figure out how to solve this problem.

I can live with a .2 difference with a standard or target loading.