RCBS Uniflow Powder Measure Issue

[Jaywalker]

In setting up my new RCBS Uniflow Powder Measure, I installed the smaller diameter plastic drop tube, as the instructions indicated it was for .22 to 7mm cartridges. I eventually removed it, as it was suficiently erratic as to be unsafe.

For instance, a down stroke might drop nothing, or maybe two complete charges. An upstroke might or might not drop something. Inbetween, small amounts would drop at different times.

I eventually figured out that the powder (4064) wasn't feeding reliably, and was stuck in the top of the drop tube. A tap or a motion would drop something, but seldom the full amount, and only the full amount, I wanted.

Putting the larger (.30 cal+) drop tube in fixed the problem for me, but this seems to be a dangerous oversight in a powder measure that newbies (like me) buy in a reloading kit.

Am I overlooking something, or is this something I should bring to the attention of RCBS?

Jaywalker

 

[stans]

Powder sticking, called bridging, in drop tubes is a fairly well known problem in most powder measures. Trying to get stick or large flake powders to flow through small diameter openings can be a real task.

 

[Jaywalker]

Thanks, I'd seen the term "bridging" in a recent thread, but didn't know what it meant.

Jaywalker

 

[Ala Dan]

ATT: Jaywalker

You have discussed a common problem with all types
of powder measures that I have experience with;
except the old Pacific DeLuxe Measure (now its
called "Lok-N-Load" as manufactuered by Hornady).
I offer two suggestions, and the first may or may
not help matters regarding your situation? First,
you need a powder baffle; available from RCBS,
Redding, etc for about $6.50; or very easily made
from a piece of aluminum, such as gutter material
or the like. Mine is approximately 1.5" wide, x 4.5"
long, and is bent in the middle; with a small flange
on either side of the foot. Insert this atop your
desired powder, and be sure to put the lid back
on securely. What this does is to put pressure
on the powder in the hopper; while you are using
your "Uniflow".

#2: After you are satisified that the "Uniflow" is
operating correctly, MAKE CERTAIN that each stroke
of the arm is the same. I use a RAPID motion, and
bump the arm at the end of the stoke to ensure
that there is no build up of powder in the "throat"
of the drop tube. Hope this helps, my friend?

Best Wishes,
Ala Dan, N.R.A. Life Member

 

[swifter]

NONONONO!!!

The baffle does not go on top of the powder!!

It goes at the bottom of the plastic hopper, just above the metal body.

The purpose is to limit the amount of powder pressing on the "works".

For cheap, get a fender washer with a minimum 7/8" hole in it that will just slide into the hopper and rest on the metal body. About $1.75...

 

[Edward429451]

The long grain rifle powders are nortorious for that. I've had the same problem with 4064. Like Dan said, knock the handle a pretty good knock on the up stroke and on the down stroke while striving for consistency in stroke force. The vibration of the knocking helps assure that all the powder drops consistently. A give a slight pause at the top stroke to give the powder time to fill the cylinder. Some larger charges can take the better part of a second or so to drop the entire charge. So don't be in a big hurry here.

Don't baby that powder measure, you wont hurt it. Mine's still going strong at around 15 or 16 yrs old.

Good shootin'

 

[Jaywalker]

Thanks, all, for the ways around this issue. Using the larger drop tube seemed to work okay for now for 4064; it fed very consistently. I did move up, knock, and pause, though it didn't occur to me to wait as much as a second to allow the cylinder to fill, so I'll incorporate that immediately. (I did learn to put newspaper on the floor under the tube, so I could hear when things hit the paper; paper sound, dump the powder back into the hopper. Maybe I need a powder measure stand so I can see this happen, instead...)

The extruded powder must be noticiably better than ball for us to put up with this issue... I'll try some ball, next time.

Jaywalker

 

[Steve in PA]

Its the type of powder, not the powder measure. I use IMR-4895 for loads in my M1 Garand. I've used IMR-4064 and 4350?? in other .30/06 loads.

I measure (weigh) every load when using these powders. Just because you didn't get any "paper sound" doesn't mean your powder charge is good.

I set my RCBS to throw slightly under the charge I want, then trickle powder into it (on the scale) until it measures what I want.

I use HS6 and H110 for my 9mm and .44mag.....these powders measure great. I can throw charges all day and they'll never change.

 

[Ala Dan]

Agreed, with Steve in PA! The RCBS Uniflow
also works great with Hodgdon's Universal Clay's.

Best Wishes,
Ala Dan, N.R.A. Life Member

 

[Jaywalker]

Well, once I got it working, it threw very consistently. I measured each of the first 10, and they were within 0.1 g. I went to every fifth one for the rest, and the test for each series was within 0.1 g. Is there something about 4064 that makes it necessary to measure each one?

Jaywalker

 

[Steve in PA]

Its just the type of powder.

Ball or flake powder measures very well. HS6, H110, H414 and Unique all meter extremely well.

Extruded or stick type powder, IMR-4985, 4064, 4350......for the most part, don't meter very well. You can tell this by the "crunching" for lack of a better term of the powder when you use the measure. Its actually the drum cutting the stick powder.

Plus, the ball or flake powder more uniformally fills the drum, than the other powders Which is why I said, when I load IMR type powder for my rifles, I weigh each charge, just because I like uniformity

I still weigh each charge og H414 when loading for my hunting .30/06..but I hardly ever have to trickle anything in to the pan.

 

[Edward429451]

The foremost would be safety (knowing that the long grains may bridge, don't want a squib load!) and the second would be for performance. 4064 is an excellant powder that can deliver super accurate loads. Many Olympic types or other competition shooters use 4064 to win and set records with.

Hand weighing each charge ensures consistency which translates into more accurate loads. It may seem like a pain in the butt but it is worth the effort.

I had one single round of 4064 bridge on me so I started hand weighing each charge also.

 

[Jaywalker]

Certainly, as a newby, I'm not in a position to disagree, but I've recently read here (comments to mtnbkr re his 6.5X55 reloading beginning) that the small difference of a quarter grain makes no noticable difference to group size. I certainly understand the safety concern, however. When I threw (in lieu of "measured"), I set them all up in the block and visually inspected all the filled cases at one time with a flashlight for obvious squibs/overs. At this point I was also at starting load and up to mid-load levels only. I think I'm reasonably okay against catastrophes - hotter loads I'm measure.

Yes, I think "crunch" is a fine term. I experienced it a lot.

Edward429451,
Interesting about the high accuracy and Olympics - I hadn't know that. I chose 4064 because of its low volume requirement. Low volume, I believed, would translate into lower muzzle blast, flash, and recoil effect, in an already low-effect cartridge. High velocity wouldn't do me much good with Hot Cores, anyway. It looks as if I made a good powder choice accidentally.

Jaywalker

 

[Chainsaw]

Jaywalker, I am told the relatively inexpensive Lee powder measure that sells for around 20 dollars works fairly well with extruded powder.

I have the RCBS Uni-flow and use strictly ball type powder for all my loading. I was reminded this past week of how much I dislike extruded powder when running some loads for a 7mmSTW using 4831 SC powder and it "bridged" in my powder measure.

I had a benchrest rifle(since sold) that I could only get to shoot right with extruded powder and loaded those cases with just the scale and Lee dippers and then the trickler.

If you take a liking to ball type powders, I have found several that worked for all my loading needs. I load .223, .243, .284 Win, 7mmRem Mag, 7mmSTW .308, 30-06, 30 Carbine, and 9mm Parabellum........Chainsaw

 

[BluesBear]

Not to pick on any one person

I have seen several people, recently, get this wrong.


...you need a powder baffle;...
...Insert this atop your
desired powder...
...What this does is to put pressure on the powder in the hopper...

NOPE, Wrong, nuh-uh, nyet, Nein, ain't right.

Why do you think they call it a baffle? Baffles do not float on top.
The powder baffle goes in the BOTTOM of the reservoir.
A weight piece of aluminum this size would be neglible as far as the pressure applied. If you wanted weight you' use steel or even lead.
Its design is to limit the pressure applied to the powder flowing into the measuring chamber.
The LAST thing you want is more weight on the powder. That would cause the powder at the bottom to compress and since a powder measure, measures by volume instead of weight compression increases the charge weight.
The baffle REDUCES the weight felt by the powder at the bottom.

I am reasonably sure that the instructions that accompany the RCBS baffle indicate that it should be used at the bottom of the reservoir.



As for the powder sticking in the drop tube. My Uniflow is now 25 years old and it has aluminum drop tubes. I always wiped the reservoir with an anti-static dryer sheet whenever I changed powder.

If you are using plastic drop tubes there is a possibility that static could be causing the powder to stick to the tube and not drop properly.

I also used a "double tap" technique when I was looking to the most uniform results. I raise the lever to the top and then slightly tap it a second time and then lower the lever and tap it again. So it sounds like, tap-tap......tap-tap. That way the powder vibrates slightly in the reservoir setteling nicely into the measuring chamber on the up-stroke and also ensures that all flows out on the down-stroke.

I weight EVERY 10th charge on standard loads and every 5th on match grade loads. If any weight charge isn't right I dump the last TWENTY and redo them weighting each and every bloody one of them. If I get 20 that are good then I'll go back to the 5 or 20 rule.

I loaded around 2 million rounds commercially in the 1980s and I had a guarantee that stated that if one of my customers ever had a round that wouldn't fire I'd replace it with an entire box of the same ammo. No one ever took me up on it.

 

[Ala Dan]

Guess I need to invest in a REAL

Powder Baffle, don't I?

or better yet,

a Hornady "Lok-N-Load" Powder Measure.

Best Wishes,
Ala Dan, N.R.A. Life Member

 

[bogie]

Well, on my $225 Harrell measure, I whack the handle on the upstroke, and on the downstroke. I _try_ to do it the same each time I use it.

If I load long stick powders, I use my $30 Lee measure.

 

[Ala Dan]

Powder Baffles

Well, I just solved my powder baffle problem! You
see, I found a flat washer that will fit flush near the
bottom of the RCBS "Uniflow" powder measure with
a small hole dead center. This probably will be able
to control the amount of powder entering the meter
cuz it fits a flush 360 degrees.

Best Wishes,
Ala Dan, N.R.A. Life Member

 

[BluesBear]

This probably will be able to control the amount of powder entering the meter cuz it fits a flush 360 degrees.

Well yes and no.
Mostly no.

The washer just presents a smaller aperature for the powder to flow through. It does nothing to address the issue of the weight pressing down.

The advantage of the "pup tent" baffle is that it allows the powder to flow around the edges to get inside the baffle The "sides" of the baffle support the weight. The baffle decreases the direct pressure felt by the powder at the bottom. The more equal the pressure exerted on the powder the more uniformly it will meter.

The problem with the washer, even if you elevated it, is that in order to maintain a pathway the powder can flow through without clogging, the opening would be too large to adequately regulate the weight. And since the Uni-flow meters from the center you will still have a wider pressure fluctuation than you'd have if the powder passed by the baffle on the sides.

 

[308win]

I make baffles for my RCBS out of 2 liter bottle caps. Cut outs in the sides take the pressure from weight off yet let the powders I use flow freely to fill the drum. (I haven't used any stick powders for quite awhile, when I was using them I used a Lee dip measure and scales.

 

[Ala Dan]

Well, I just loaded a batch of 9m/m ammunition
this AM, using the "washer baffle". Virtually no
problem, as the powder (Alliant Bullseye) flowed
very evenly and did not build up around the drop
tube. Guess I will continue using it!

Best Wishes,
Ala Dan, N.R.A. Life Member