RCBS uniflow measure. Accuracy going away.

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CoreyMac

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Have any of you guys found your uniflow powder measure loosing accuracy? I've had this one for 25 years and it's been good. All of a sudden it throws loads that are quite different. Up to a full grain sometimes worse. I have found myself loading in the middle of a spec to compensate for the up and down so I don't get into the danger zone. I've cleaned it , I always hit the stops good, I.make sure the powder level is consistent. I use ball, and flake in it mostly. Doesn't matter if it's a large load or small. I'm loosing confidence in it. I can't see it wearing out. I check everything for looseness regular.

It's to the point where I can feel the difference in my rounds shot to shot , is it time for a replacement or a different unit?

Thanks
Corey
 
Maybe you’ve already tried a balance beam scale but I ran into the same problem you are having and it was my digital cheapy scale. Balance beam said the uniflow was on the money every time and my groups reflect that.
 
woodenpigeon said:
Maybe you’ve already tried a balance beam scale but I ran into the same problem you are having and it was my digital cheapy scale. Balance beam said the uniflow was on the money every time and my groups reflect that.
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Funny I was thinking that also. I have a beam scale but put it away for the digital, I'm going to bring it out again. I guess don't mess with old school methods.

Corey
 
CoreyMac said:
Funny I was thinking that also. I have a beam scale but put it away for the digital, I'm going to bring it out again. I guess don't mess with old school methods.

Corey
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If its not your "digital cheapy scale" your getting older and your arm may be out of calibration. I bought a RCBS ChargeMaster Combo, put my battery powered digital cheapy scale away and don't worry about my arm being out of calibration.
 
A baffle will help ...Maybe

Large drum or small drum

Clean with a alcohol sheet let dry.. rub with a dryer sheet (static)

Is it below the drum problem ... bridging
 
PGW Steve said:
It's a pretty simple mechanically set volume, hard to see that changing over time. Do you have the powder baffle in it?
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No powder baffle, I just ordered one. I'll clean the unit as suggested and install the baffle. I plan to make 5 or 6 hundred rounds of 45acp this weekend so I'll give the measure a try when I clean and make the mods.

I'll get back after a test.drive.
Corey
 
CoreyMac said:
Funny I was thinking that also. I have a beam scale but put it away for the digital, I'm going to bring it out again. I guess don't mess with old school methods.

Corey
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The cheaper digitals can wander in some conditions, always check with the beam scale if you see funny things happening.

Also - isn't there two different rotors that come with the Uniflow powder measure - one for rifle and one for pistol? Are you using the right one?
 
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jethunter said:
The cheaper digitals can wander in some conditions, always check with the beam scale if you see funny things happening.

Also - isn't there two different rotors that come with the Uniflow powder measure - one for rifle and one for pistol? Are you using the right one?
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I installed the pistol rotor when I first got the unit and never changed it, I.never reload rifle rounds. It's been working great for over 20 years now it's off a bit. But again, I'm using a new.digital scale to weigh my powder and now things are off. I'm leaning to the scale being off, but when I shoot i can feel a marked difference in power from round to round. This is telling me that the powder measure is actually putting out different amounts.

Odd to say the least.
Corey
 
I have the same measure, and with the pistol rotor installed, I find a minimal charge, say 3.0 grains, can be off about .01 grain either way. That's nothing to be concerned about.
 
There is a possibility that your measure is wore enough in one spot to cause a problem, I have only ever seen it on one measure and that was my old mans, that. like yours he used for years ( 40 yrs in his case). Where we discovered the wear on his was in the cast body where steel tumbler/roller cuts the powder at the lip. The cast is somewhat "softer" more prone to wear than the steel roller. The lip on the cast frame had wore enough that it was throwing inconsistent charges...sometime powder from the hopper would migrate into the wear area sometimes it would bridge over and be accurate but there was no telling when it was going to happen.
 
fingers284 said:
There is a possibility that your measure is wore enough in one spot to cause a problem, I have only ever seen it on one measure and that was my old mans, that. like yours he used for years ( 40 yrs in his case). Where we discovered the wear on his was in the cast body where steel tumbler/roller cuts the powder at the lip. The cast is somewhat "softer" more prone to wear than the steel roller. The lip on the cast frame had wore enough that it was throwing inconsistent charges...sometime powder from the hopper would migrate into the wear area sometimes it would bridge over and be accurate but there was no telling when it was going to happen.
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Ok,good information. Before I start loading on Saturday I'm taking the whole thing apart for a clean and inspection, I'll look at the spot you mention.

Corey
 
I never got as consistent charges with my RCBS throwers, the real solution is to install the micrometer upgrade. My Redding charger is very consistent.
 
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