Optimizing the RCBS Uniflow For Stick Powders

[Warm_Garand]

I reload for the Garand, and my RCBS Uniflow powder measure was dropping IMR 4895 badly--we are talking about half-grain variations, and that just wasn't working for me.

I tried adding the internal baffle* (highly recommended mod) but it was still throwing inconsistently--three- or four-tenth's grain variation, and trickling charges was taking WAY too long.

I had read a thread on another board about polishing a Dillon 550 powder hopper, the poster claimed that it smoothed out the throw to within 1/10 grain, even with stick powders like Varget, so I figured I'd give it a shot on the RCBS Uniflow.

The guy in the thread talked about grinding and buffing and polishing with a dremel tool to smooth out the finish of the cast-aluminum-- polishing for hours.

A couple or three hours? Ummm. Yeah--no.

Me, I just got Medieval.

NOTE: PHOTOS WERE ALL TAKEN POST-REASSEMBLY.

COMPLETELY DISASSEMBLE THE POWDER HOPPER DURING THE GRINDING AND POLISHING PROCEDURE.

I used a 3/8 inch drill--a 3/4" wire brush--driving a biscuit or coarse steel wool, which shapes itself to the inner contours of the hopper--and drive a cone-shaped sandpaper abrasive to do your cutting/polishing. Yeah, Baby--cuts FAST. Beats the whine of a dremel tool hand's down.

I did a rough cut with wet-dry sandpaper, then went with progressively finer cuts--320, 400, then went to biscuits of fine steel wool, THEN I went to a dremel tool with polishing rouge. Total elapsed time is maybe 45 minutes, soup to nuts.

You can use the dremel stone to good effect down in the throat of the powder hopper. I decided to break the sharp edge where the cylinder rotates (NOT the black rotor--just the green casting), just slightly soften the sharp edge--and I noticed that now it feels much smoother and less gritty and cuts WAY fewer grains of powder.

After you are done with the polishing phase, wash the powder measure real good with hot soapy water, rinse it well, dry it off, then coat it with paste wax (I used Johnson's Paste Wax). When the wax sets up good, polish it to a luster with a soft cloth. Maybe wax it twice--the smoother, the better.

I ran a pound of old pistol powder (flake) through the Uniflow just to lubricate it good--SR 4756, then started dropping charges with IMR 4895. I used no special technique (on purpose) I just lifted the handle smartly and let go and let it drop from it's own weight. My first ten throws were within a tenth of a grain--with IMR 4895(!). I was a very happy camper. Now, I have noticed that when adjusting your charge weight you have to tweak the cylinder volume back and forth just a little when setting your throw, just to find the sweet spot--but the powder throw is astoundingly more consistent with stick powders, and I rarely feel the rotor cutting grains anymore.

If you throw a lot of stick powders, definitely think about doing the mod.

I'm guessing you'll be very happy with how your Uniflow drops powder.

Good luck.

--Warm_Garand

*LINK to powder baffle (though you can probably make one yourself for 5 cents LOL):
http://www.midwayusa.com/viewproduct/?productnumber=493217

 

[DukeInFlorida]

Consistency still has a LOT to do (with this powder measure) with the packing of the powder in both the powder cylinder, and in the adjustable "hole" in the hub. A consistent series of taps (up and down) assure that the powder will flow and pack the same every time.

I love the Uniflow dispensers, and have several of them, large and small hubs, available for my use.

I'll be doing a ton of IMR 4198 here in the next week. Always within .1 grains, and have never done any mods (don't even have the powder baffle). Tap tap, tap tap...

 

[Kicker96FS]

Yep, hit it twice to assure a packed, full, consistent load. Up, down, up, down, dump. Or as Duke says, Tap tap, tap tap...

 

[Warm_Garand]

Interesting comments.

So do you guys think it's a question of the powder measure "breaking in" or "lubricating" with age as well? Do you get consistent 1/10th Grain throws with a newly-prepped straight out of the box Uniflow?

I couldn't have been more consistent with my throw-technique (TapTap/TapTap) and I was still getting huge variations with my throws until I did this mod. Also: now there is no TapTap/TapTap involved--it's just Lift Smartly/Drop it.

--Warm_Garand

 

[Kicker96FS]

Cool, I have always done it this way because I was shown that it was the way to do it, and always have had consistent loads.

Looks like your efforts have paid off! Nice write-up BTW.

 

[Slowdive]

I'll be doing a ton of IMR 4198 here in the next week. Always within .1 grains, and have never done any mods (don't even have the powder baffle). Tap tap, tap tap...

How does the Lyman #55 measure differ from this powder measure? IMR 4198 is one that I have a real problem with, so much so that I am re-developing my loads for it with RL7 (not ideal cause 4198 is better for certain loads). It's like a wrestling match getting that lever to spin when those long grains cross the cylinder and weight consistency isn't great. Intuitively I'm not grasping why polishing the hopper base would help, but I'm up for trying it.

 

[DukeInFlorida]

I get consistent measures with my tap-tap-tap-tap system. Always have.
Even in a brand new or even an old Uniflow. I bought several for my reloading classes, and they work like a champ.

A few things are important:

1) Fill the Uniflow to the top, even if doing just a few. That gives good column weight pressure to accurately fill the pocket.
2) Settle the contents of the powder measure by tapping on it or a few minutes. Longer than you think you should. That gets the density packed and consistent.
3) Run a few tap tap tap tap dumps back into the dispenser before starting to check any weights. That gets the powder "aligned" in the column.
4) Develop a rhythm and a firmness to the tap tap tap tap, and stick with that. I often have student prove the point by over tapping, and watching while they see that the weight changes considerably. That's because you're affecting the density of the powder packing into the pocket.
5) On a long run, refill the powder dispenser when the powder gets down below 1/2. Settle the powder again, and do some samples before proceeding with powder dumps.
6) Make sure you have the right hub installed for the job. Small hub for pistol, and large hub for rifle. The Uniflow comes with the LARGE hub installed. That is suitable for 25 grains and up. Don't try to dispene 5 grains of powder with the large hub installed. That's like a single layer of powder.

I've been running my Uniflows this way for 35+ years, and I always hit that level ( .1 grains or better) of accuracy. When I work up my statistics, my dispenses are typically .02 grains or better. That's point oh two.

 

[bpm990d]

Thanks for posting. Great pictures.

B

 

[Jose]

I'm gonna tear into mine and do this. Makes all the sense in the world.

While Duke's method works (I do it too), ANYTHING that reduces the need for special techniques and human skill in a production process is worth doing.

 

[Warm_Garand]

I'm going to hazard a guess (and it IS just a guess) that all the "tapping" does is overcome gliding friction and compact the stack of powder until it has as little variation in the hopper as physically possible . Polishing and smoothing away the rough surface of the hopper also reduces the "drag" of the powder feed (guess: which The Duke is overcoming by "tapping") allowing gravity itself to have a more pronounced compression effect on the stack of powder.

The idea here is for new guys like me to be able to bypass all the exquisite technique which Duke has accumulated over the years. (Sorry, Duke).

The sandpaper cuts quick--but I'd guess the major benefit is of the mod is gained in the felt pad/polishing rouges. If you don't have a Dremel, they can be had now (generic brand)) for as little as $15.

Another way to overcome the drag is to strap a simple aquarium aerator to the hopper (you can find them at Walmart). Reloaders say the constant vibration of the aerator also helps to settle the column of powder. I don't know how annoying the hum is--I'll pick one up, give it a try, and post back.

Good luck.

--Warm_Garand

 

[swampy]

How is the tap tap tap tap method performed if you have the uniflow on a progressive press with a case activated operator?

 

[Warm_Garand]

How is the tap tap tap tap method performed if you have the uniflow on a progressive press with a case activated operator?

The fellow who posted the original mod was attempting to overcome the limitations of throwing stick powder in a Dillon progressive press. Apparently he succeeded.

Link:

http://forums.1911forum.com/showthread.php?t=154783

I just figured hey, I had nothing to lose.

--Warm_Garand