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Old May 10, 2012, 06:52 PM   #1
serf 'rett
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RCBS Uniflow – Heads Up Ye Users

Powder Measure is RCBS Uniflow. Single stage press.

I was loading in batch mode a few nights ago; had adjusted the powder measure to meter the desired amount of Power Pistol powder and loaded the first 50 9mm rounds. I normally only charge 50 cases at a time, but decided to drop powder into a large batch of 200 cases, so powder was dropped into 4 trays with 50 cases per tray and the trays set aside.

I’ve used the powder measure for a while and have found the Powder Pistol to meter very consistently with little variation; therefore, everything seemed normal when I followed my standard practice of dumping and weighing the powder in the first and last case of the first tray of 50 charged cases. Bullets were set and life was lovely…until I happened to pick up tray number four next and I got an eye opening plunge of the scale pan revealing a significant increase in powder weight. What?! I carefully looked into the remaining 150 cases but could not see a difference in the powder levels. To investigate, I weighed the powder in round numbers 51, 60, 80, 90, 100, 130, 150, 180, and 198 and found that the powder weight had steadily crept up over the last 100 throws. What was going on? I’ve never had the Uniflow creep out of adjustment before; just set it and it’s set.

When I reached over the check the measure, I found the bushing, which screws into the drop cylinder and through which the charge adjusting screw passes, was loose in the cylinder. It then was obvious that as the bushing backed out, the powder charge increased.

This type of thing can give me the be-gee-bees and confirms that old carpenters adage of “measure twice, cut once,” which is a way of saying be sure before proceeding.
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Old May 10, 2012, 09:33 PM   #2
mmb713
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Yikes! Thanks for the info. Checking my Uniflow now...
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Old May 11, 2012, 02:39 PM   #3
brickeyee
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Get a micrometer head.

No set nut required.
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Old May 11, 2012, 02:53 PM   #4
DFrame
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Part of my reloading regemine is to check the tightness of everything, every time, before I start. I've found mine to be loose on a couple of occasions.
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Old May 11, 2012, 03:04 PM   #5
NWPilgrim
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Quote:
Get a micrometer head.

No set nut required.
Exactly. I did that early on on it has worked perfectly for 20+ years for both pistol and rifle loads.
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Old May 12, 2012, 08:53 AM   #6
MADISON
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My UNIFLO measure

After about 30 years, my UNIFLO powder measure go to where it would not
throw 2.0 grains of powder, as advertised.
I e-mailed RCBS and they sent me a new cylinder and adjustment stim.
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Old May 12, 2012, 05:43 PM   #7
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I usually check my Uniflow before I start dumping,, now I'll be more diligent.
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Old May 13, 2012, 05:25 AM   #8
rebs
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I check every fifth case to make sure the powder charge is correct. It may take a little extra time but it gives me peace of mind

What is a micrometer head and can I get one for my older rcbs powder measure ?
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Old May 13, 2012, 10:09 AM   #9
brickeyee
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The micrometer head should fit any Uniflow, just make sure you get the correct size (large vs. small).

They have graduations and more easily read numbers than the stock suit, and use an o-ring as a friction lock on the adjustment thimble.
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Old May 13, 2012, 11:58 AM   #10
math teacher
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Thanks for the heads up. I have been using a Uniflow for 40 years and never had a problem, but the next time????
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Old May 13, 2012, 01:27 PM   #11
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will keep an eye on it, thanks....
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Old May 13, 2012, 02:51 PM   #12
chiefr
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I have seen this problem before, when you change cylinders and only finger tighten the nut. I make sure I slap a 3/4 wrench on the nut everytime I change cylinders. As a matter of safety, I keep the wrench next to my uniflow.
Thank the OP for bringing it up.
I also stuck a 3" flourescent orange shooting dot on the powder reservoir on my Chargemaster with words "Check dump valve before filling"
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Old May 13, 2012, 08:02 PM   #13
serf 'rett
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Just to be clear. The stem and the locknut, which is on the stem, did not change or move. It was the bushing, which holds the stem., that backed out. I suspect the micrometer setup could do the same thing since it screws into the cylinder the same as the adjustment screw bushing.

A micrometer is on the short list; however, every time I get close to ordering, I end up ordering just a "few" more bullets.
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Old May 14, 2012, 04:02 PM   #14
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Quote:
I check every fifth case to make sure the powder charge is correct. It may take a little extra time but it gives me peace of mind
That’s what I do it gets rid of that big surprise when you pull the trigger. Also look in the cases in the loading block before starting to seat the bullets. Being in a hurry reloading is like drinking and driving it will eventually get you in trouble .
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Old May 15, 2012, 01:31 PM   #15
JimBobTX
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I hardly use my Uniflow anymore. My RCBS Chargemaster is spoiling me...LOL
I'm gonna have to look into the micrometer head for mine too. Then I might use
it more often.
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Old May 15, 2012, 11:59 PM   #16
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Quote:
Just to be clear. The stem and the locknut, which is on the stem, did not change or move. It was the bushing, which holds the stem., that backed out. I suspect the micrometer setup could do the same thing since it screws into the cylinder the same as the adjustment screw bushing.
If you don't run the bushing in tight, it will loosen up with repeated tapping on the powder measure body. On top of that, dragging the bushing down one side of the slot it rides in, while throwing charges, can quicken the action.

Get a wrench on it.
You don't have to smoke it down, but hand-tight is no good, either. Snug with a wrench is all you need.
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Old May 17, 2012, 10:26 AM   #17
serf 'rett
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Quote:
it will loosen up with repeated tapping
Correct!

Quote:
Get a wrench on it.
Did that when I swapped over to the small cylinder, but I snugged up the sucker instead of torqueing it. The surprise, of the bushing backing out, was mostly due to it happening after I had already loaded over 4K rounds prior to the problem occurring.

Got to go get my big wench, er…wrench to tighten the thing
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Old May 18, 2012, 12:38 PM   #18
brickeyee
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Since the micrometer heads lose zero if you exchange from large to small cylinders in the Uniflow, I have a pair of Uniflows.

One large, one small, each with a micrometer head and powder baffle.

I can dial up very close to perfect loads across multiple calibers even years after the fact.

The settings are in the log book right beside the load.
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Old May 19, 2012, 05:12 AM   #19
Mike / Tx
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I have found the loose bushing issue with mine in the past. I used a bit of teflon tape and when I screwed it back in made sure it was secure. Haven't had the issue arise since.

I also addd in a spring washer between the adjustment nut and the bushing on the stem. THis makes it a bit more secure and easy to adjust the stem without having to loosen and tighten the ring every time. Simply loosen the ring, tweak to the charge wanted and tighten. More or less it acts like a lock washer.
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Old May 19, 2012, 12:32 PM   #20
billcarey
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I snug them up with a wrench...but the spring washer is a major improvement compared to one without.
bc
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Old May 19, 2012, 03:03 PM   #21
Cornbread
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I like the spring washer deal. Where is a good place to get them ? Lowes ?
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Old May 19, 2012, 03:45 PM   #22
serf 'rett
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A spring washer? Now that is interesting. I started to dash off a quick reply that you can get one from RCBS, because my 1.5 year old Uniflow came with a spring washer; however, when I pulled up the instructions, no spring washer was shown. Huh...?

Then I downloaded the RCBS Parts Book and saw on page 18, Item #13 Part #09260 - Bow Washer.

The Bow Washer is the cat's meow for we of the plebian class (non-owners of the highly vaulted Micro Gizmo!). With a little tinkering, the tension on the bow washer can be set in such a way that small adjustments can be dialed in without needing to loosen and tighten the lock nut.
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Old May 19, 2012, 07:09 PM   #23
Mike / Tx
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Quote:
The "Bow Washer" is the cat's meow for we of the plebian class (non-owners of the highly vaulted Micro Gizmo!). With a little tinkering, the tension on the bow washer can be set in such a way that small adjustments can be dialed in without needing to loosen and tighten the lock nut.
Yea one of those things, ^ LOL I call then spring washers but didn't know RCBS had a technical term for them or that they even listed them. My Uniflows are all pretty old and were purchased second hand. But yes that little washer is a dream to use when tweaking in a final charge at the range.
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Old May 20, 2012, 10:15 AM   #24
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I think they're also known as a Belleville washer. Real handy little buggers, and sometimes not-so-little as they are used in diaphragm-style automobile clutches.

Semi-OT but IIRC Hornady provides them to LnL AP owners upon request if their powder measure keeps working loose from the press head. Not an uncommon occurrence.
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