How much faith do you put into a Uniflow powder measure?

[chewie70]

I just want to say that this site has been such a valuable resource for me, as I am new to reloading pistol rounds. All in all, everything has gone well, but I have had some minor issues and was wondering how much faith people put into there RCBS Uniflow powder measures as far as consistancy and accuracy? I want to say ahead of time that I'm sorry for such a long post. I just want to make all of the facts available.

First off, my equipment is an RCBS pro 2000 press with supplied Uniflow PM and baffle. I had also purchased an RCBS 10-0-10 scale and recently purchased an RCBS charge master 1500 scale which I have yet to use. I thought the 10-0-10 seemed cheaply built and may be the cause of my problem.

The loads in question are for the .45 acp as follows:

Speer 185gn TMJ match bullets
Bullseye powder @ the min. load = 4.5gn
Federal 150 large pistol primers

Now for the problem that existed with my first set of loads, haven't had a chance to fire the second round yet.

I installed everything according to the manufacturers manuals for the powder measure and scale. I checked the scale with an RCBS weight set and everything was right on. To break in the powder measure, I went above and beyond what RCBS recommends. I degreased everything and once set up, ran about 50 shells through the powder measure until I was consistantly getting the correct charge. I then ran an additional 100 shells through while measuring every third one.

Now it was time for the first reloads. I made 40 rounds, weighing every 5th charge and eyeballing every round for consistency prior to bullet seating. Throughout the whole process, everything went fine. The only so called problem that I experienced was with the lockout die, which I ended up removing prior to making the rounds. I was unable to set it and it seemed to always be "locked out". The few times that it would work, the rod would fail to return and the plunger would have about .05gn's of powder stuck to the bottom of it.

Now for the first test fires of my newly reloaded rounds. I shot them in groups of 5, checking the target to make sure the bullet left the barrel and also checking the fired cases for any signs of malfunction, pressure ect.... Of the forty rounds fired, 2/3 of them jammed on ejection. I linked this to the charge being to low for round and gun. There were now delayed fires or misfires. There were a few jams while feeding, but that was due to the previous round not ejecting completely. Nothing major or out of the norm.

Finally, the problem that brings me to my question about the powder measure. Out of the 40 rounds that were fired, there were 3 rounds that were "Hot". Going by sound and felt recoil, probably 2-3 times hotter than what they should have been. No apparent damage was done to the pistol or the shell casings. Is this a problem with the powder measure, am I doing something wrong?

Again, sorry for such a long post. I would just prefer that this doesn't happen again, possibly damaging my gun, and /or causing injury to myself or someone around me. I would really appreciate any feedback.

[azredhawk44]

With extruded rifle powder on my Uniflow, I get as much as 0.3gr variance, but that is the most variance I ever get. That's from top of the hopper down to the bottom, with no powder baffle.

With handgun disc/flake powders like Unique or Titegroup, I get typically about 0.1gr variance. I can't tell the difference between a hot load or a short load when a typical load is set for 5.0gr and I get either 4.9 or 5.1.

Sounds like something isn't set up right, or you have a lemon. Unless you weighed it all coming through (which it sounds like)...

You mentioned that you were using a minimum charge. Many reloading manuals will warn you against dropping below a minimum charge for a given load, and that a form of over pressure can occur due to a drastic change in the combustion properties, since the case volume allows for significantly more oxygen due to the missing powder. Win296 and H110 are the only 2 powders I am aware of that have this concern... perhaps Bullseye is succeptable to this as well?

I'd recommend up-ing your charge to something half-way between min and max for Bullseye 45acp loads. See if the felt recoil stabilizes at that point, and if the FTE continues.

[chewie70]

Thanks for the reply. That may be what it is, just don't know. As I stated, it was only 3 rounds that did this and it was a noticeable difference. Kind of the difference between a .38 and 44 mag. When I say I was using minimum loads, I was refering to what the Speer book said. The minimum was 4.5gn, and I believe the maximum was 5.0gn or something. I went with 4.5 for my first rounds. I did increase that to 4.65 for the second set, just haven't had had a chance to try them out yet.

Thanks for the info regarding too minimum of a charge, it makes since. I'll have to research that one. That's what I love about this site, always learning something new.

[XD-Guy]

chewie, I'm in the market for a 10/10 scale if you don't like yours maybe we can work out a deal

[chewie70]

Thanks XD guy, I'll let you know if I decide to get rid of it.

[Unclenick]

Azredhawk44,

You've got some information on low loading density pressure spikes misplaced. The phenomenon you are referring to is called detonation. It was first widely publicized many years ago when light (a few grains) loads of surplus 4831 burst actions in small game squib loads in .30-06 size cases. Detonation isn't well understood. Any powder can cause it, apparently. There are pictures near the bottom of a Finnish web page of a .308 that was burst by 3 grains of VV N320, a fairly fast pistol powder.

The issue with avoiding light loads of H110/296 has nothing to do with detonation. This powder is used in magnum loads often fired in revolvers. It is hard to light and needs good pressure to remain lit. If you load it down more than about 3% from recommended loads, you risk that the pressure drop that occurs when the bullet base passes the barrel/cylinder gap in a revolver will cause the load to squib out, leaving a bullet stuck in the barrel. If the next shot is fired with that bullet stuck in the barrel and does not squib out, the gun may burst. Hodgdon's site has a warning explaining this.


Chewie70,

Flake powders, like Bullseye, are known to bridge occasionally on their way into a measure’s metering chamber. That usually reduces a load, but if the bridge breaks when the metering chamber comes mouth-up for the next round, it can dump a lot of powder in suddenly, which packs it. I've had a double charge go off in a 1911 .45 ACP before. It burst the case, cracked the wood grip panels, dented all the cartridges in the magazine, jammed the gun partway into counter-battery, swelled the barrel a couple thousandths ahead of the chamber, and threw brass fragments into my face through the gaps in the slide and frame fit of the pistol. Fortunately, I was wearing glasses. In any event, I don't think you are double-charging, or you’d have a greater complaint. However, you can still have a significant fractional increase in charge. Even half a grain extra can feel significantly warmer in a Bullseye load.

Flake powders are also sensitive to static electricity hanging them up. Wipe the inside of the powder hopper out with an anti-static computer screen wipe or with one of those clothes dryer softener rags that come on a roll. Let it dry. Next, run a can of powdered graphite through the measure to lubricate it and also help fight static. My old Uniflow came with two drums. Assuming that hasn't changed, be sure you are using pistol powder drum with smaller diameter metering chamber.

Flakes also get cut easily by a drum measure. That means they jam in the edge of the drum. This can jar the whole assembly and make powder charges vary because it packs the powder in the hopper, causing subsequent charges to weigh more. Be sure you have baffle in the measure. If you don't, you can make one by downloading the PDF file in this forum thread: Make your own baffle

In general, you will find that measure performs best with ball powder. I would consider making a change to W 231 or HP 38 for similar performance to Bullseye. It will likely meter within 0.1 grains. Save the Bullseye for a Lee Perfect measure, which handles the cutting issue better. The Quick Measure by Tim Johnson won't cut it noticeably at all.

Put your lockout die back and get it working. RCBS factory service is good and they will talk you through it. It sounds like it may have been locking you out for a reason? Rubbing graphite into the plunger will help with the powder pick-up issue.

[azredhawk44]

Thanks, unclenick.

[chewie70]

Thanks for all of the info Unclenick. I'll have to mess with it and see if I can nail it down. As far as the lockout die goes, it's been replaced with a Redding competition seater so I can seat and crimp in different stages. I'm not to worried about that since I don't plan on loading anything at it's max load. I going for accuracy, not velocity.

BTW, the reason I ran so many rounds through the powder measure was to allow the graphite from the powder to give everything a good coating. Where can you buy just plain old graphite powder? I think I will also take you idea and pick up some anti static dryer towels.

[Ausserordeutlich]

I helped a friend set up his 2000 with the Uniflo measure. We made a mistake, when assembling the Uniflo, in that we didn't correctly tighten a screw that's in the micrometer assembly. Started getting inconsistent loads, naturally. Discovered the mistake; corrected same, and got consistent loads from then on. We were using AA#5, which meters well.

I wouldn't load on the 2000 without a Lockout Die. They work, if they're set up correctly. I'd give it another try.

[Edward429451]

I get +- .015 (.2) accuracy with Bullseye in my well broken in Uniflow. I get .1 accuracy with WW-231.

[chewie70]

The more that I look at it and think back to when I put everything together, I think that maybe it is just not broken in yet and I highly doubt my charges were double for several reasons. One being that there should have been some damage to the gun or case if that was the case. Secondly, when thinking back to the uniflow detup with the small pistol drum, it would be mechanically impossible to get a double charge without physically packing it into the drum since the drum measures by volume. Would everyone agree with me on this?

Regarding the lockout die, would you think that it would be unsafe practice to not use one if the above statement were true and a visual check of every round was done prior to seating the bullet? It would be visually obvious if a charge was more or less than the previous charges were, at which time you could simply pull it out and weigh it to verify. Am I correct on this? Considering that this press only has 5 stages, I would much rather use one of those stages to seat and then crimp in a different stage, instead of occupying one pf them with a lock out die. At the time, it seemed like a good idea. But now, i'm not so sure how necessary it is.

Please don't think that all of your advice isn't appreciated, because it is and I'm also learning alot. I'm just trying to think this all the way through while balancing accuracy and safety, with safety being the most important.

[CHAINSAW]

I use the Uni-flow for all my relaoding needs checking throw weights about every 15 rounds. I use only ball type powders and never have a problem.

I use AA#2, H110, BLC-2, W748, H414 and several WC surplus powders. These all meter great in the Uni-flow.

[Steve in PA]

I have total trust in my Uniflow. Been using it since I started reloading more than 15 years ago. This is a list if the current powders I load;

HS6, H110, H335, H414, Unique, IMR-4895, IMR-4064, IMR 4350

Never had a problem with them. The IMR powders can be a little tricky, but I use them for rifle reloading so I can weigh each one. I have the Uniflow set to throw a little under the charge I want then I use a trickler to get the exact weight.

[cheygriz]

I have trusted numerous quality powder measures for over 40 years, and I still have both eyes and all ten fingers!

[XD-Guy]

Flake powders, like Bullseye, are known to bridge occasionally on their way into a measure’s metering chamber

Bullseye is not a flake powder. It's a ball powder . Unique is a flake powder

[Unclenick]

XD-Guy,

You need to look more closely. Pour a little Bullseye out and use a magnifying glass. See all those little flat discs? Bullseye was introduced in 1913. The ball powder process, invented by Western around the time of WW II, was found valuable to the war effort because it allows recycling of nitrocelluose from deteriorating cannon or other aging reserves into small arms powder. It also allows the constituents to be carried in a slurry through pipes, making it easier to automate its manufacture. This, in addition to easy metering, is why there are many ball powders in use today.

[Ausserordeutlich]

RE: The Lockout Die: If you're 100% confident that you'll never EVER let one doublecharge get by you, then, of course, there's no reason to use the Lockout Die. FWIW, EVERY RCBS 2000 @ RCBS R&D is required to have a Lockout Die, according to the guy we spoke to when my friend doublecharged a .45ACP on a 2000 and blew his new pistol up.

[XD-Guy]

Unclenick,
I stand corrected. Bullseye is a flake, however it is a very small flake and I don't see how it could cause any "Bridging" at all, unlike Unique, which is a nightmare to meter in some cases.

[chewie70]

It would be nice if the powder manufacturers listed the shape of the grain for "ALL" of there powders.

Regarding the lockout die, I feel confident enough as to not double charge a round. Considering you have to look each case to prior to seating the bullet, I would think that it would be pretty obvious with a short case such as a .45acp. I'll play around with that idea and intentionally dump a couple of double charges, just to see how obvious it really is.

[Unclenick]

Chewie70,

You'll find it's really obvious.


XD-Guy,

Bridging is just a lot of overlapping pieces holding each other up the same way a random pile of overlapping playing cards spread out on a table can be picked up as a group. It doesn't need to cross the whole mouth of a metering chamber, it only needs to overhang the chamber mouth a little to throw a measured quantity off. It gets less probable that a bridge will form and hold up as the flakes get either smaller in diameter or thicker, but its not impossible. That it happens more often with large flakes is part what makes Unique notorious for being hard to throw consistently from a measure, while Bullseye only causes the problem occasionally. Static electricity can exacerbate the problem immensly by helping hold flakes together in a bridge that otherwise would collapse.

Nick

[chewie70]

Thanks Unclenick, I figured it would be pretty obvious, especially on a short/wide case. Plus, from all of my ballistics research, I highly doubt that I will be using maximum charges. So even if it is slightly over, it shouldn't be enough to cause an incident. I'm just a perfectionist when it comes to stuff like this, and want to create the perfect/accurate load everytime.

I'm thinking that I will probably take the powder measure off, fill it completely with powder and manually cycle it back into the can. Then I'll just start from scratch and see what happens.

[brickeyee]

What rotor is in the Uniflow?
The large rotor will produce more variation in very small loads.
The small rotor has a a smaller diameter charge hole and thus a small load occupies more length.
Are you using the micrometer head or the supplied screw nad lock nut?
The micrometer heads work very well. They use a friction o-ring to maintain position instead of the lock nut of the original adjustment.
With a baffle and a small rotor my Uniflow throws less than 0.1 grain of variation.
Vibration of the measure also effects powder packing, even with a baffle.
I usually run off 20-30 cycles beofre throwing ten and weighing the batch.

Since the micrometer head looses zero if you change the rotor out, I have two Uniflows. One large rotor, one small rotor, each with a micormeter head.
I can dial up a load weeks or months later and be nealry perfect.

[Ausserordeutlich]

The Uniflo on my friend's 2000 came equipped with the micrometer adjustment.

[Unclenick]

The Uniflow comes with two drums and two micrometer plungers. One drum and micrometer pair are smaller diameter than the other, and are intended for pistol and small rifle cases. The other pair are intended for large rifle cases.

[chewie70]

Yeah, Exactly what Unclenick said. Mine came with the large and small drum, large and small plunger, and micrometer. I set up the small drum and small plunger for pistol.