Question about RCBS Uniflow powder measure - Page 1

Armory » Reloading

Site Notices

[ARCHIVED THREAD] - Question about RCBS Uniflow powder measure

Posted: 1/14/2019 9:02:43 PM EDT

I am getting up to a half grain difference with my RCBS uniflow. Is this common?

Powder: RL15

Posted: 1/14/2019 9:16:49 PM EDT

[#1]

No normal in my experience. I can keep throws within ~.1g with

ball and or flake powder. Extruded powder like IMR 4064, Varget etc.

are less consistant but still within ~.2g.

Inconsistant throws can also be due to technique.

RCBS uni flow accuracy test

https://www.youtube.com/watch?v=XcKqSOGh7e0

Posted: 1/14/2019 9:50:59 PM EDT

[#2]

Ball powder, bang once up, once down. Extruded, bang twice up, once down, absolutely the same every time. And even then I will end up cutting a rod here and there - it happens, and velocities aren't very different.
Flake powders I don't mess with - 700X was such a huge PITA to meter that I gave up on any more flake powders.

Posted: 1/14/2019 9:52:34 PM EDT

[#3]

I would take the drum apart and make sure everything is dry and wiped clean as well inside the hopper. You may have some static build up or dirt in the cylinder giving you inconsistent throws. For the record, with RL15 my Uniflow throws consistently around .1gr.

Another thought is your technique. I find that on the up stroke I quick double tap the handle and that gives me more consistent throws. No matter what you do with the handle you have to be the same every time.

Posted: 1/14/2019 10:32:12 PM EDT

[#4]

Quote History

Quoted:
I would take the drum apart and make sure everything is dry and wiped clean as well inside the hopper. You may have some static build up or dirt in the cylinder giving you inconsistent throws. For the record, with RL15 my Uniflow throws consistently around .1gr.

Another thought is your technique. I find that on the up stroke I quick double tap the handle and that gives me more consistent throws. No matter what you do with the handle you have to be the same every time.

View Quote

This ^^^^ It has to be done every few years depending on how much you use it.

kwg

Posted: 1/14/2019 11:26:13 PM EDT

[#5]

The secret of using a powder measure is to settle the powder, and resettle after adjustments.

Which I explained in this post, https://www.ar15.com/forums/armory/Powder-Measure-Tip/42-479795/#i4815819

The thread my post above is in has other good PM info in it.

Then a thread I did about tuning a Uniflo, https://www.ar15.com/forums/armory/Tuning-a-Uniflow-powder-measure/42-380281/

Posted: 1/15/2019 5:43:53 PM EDT

[#6]

Quote History

Quoted:
The secret of using a powder measure is to settle the powder, and resettle after adjustments.

Which I explained in this post, https://www.ar15.com/forums/armory/Powder-Measure-Tip/42-479795/#i4815819

The thread my post above is in has other good PM info in it.

Then a thread I did about tuning a Uniflo, https://www.ar15.com/forums/armory/Tuning-a-Uniflow-powder-measure/42-380281/

View Quote

It's important to point out that most rotor-type powder measures are (usually minor) variations on the Uniflow. The Hornady Lock n Load, Lyman Brass Smith, Redding 3 and 3BR, Frankford Arsenal Platinum, and others are all similar enough to use dryflash3's tuning instructions effectively.

Basically, if it looks like a Unflow, you can tune it like a Uniflow.

Posted: 1/15/2019 5:46:43 PM EDT

[#7]

Quoted:
I am getting up to a half grain difference with my RCBS uniflow. Is this common?

Powder: RL15

View Quote

That seems bad. RL15 is about the same grain length as RL10x, right? I get roughly 0.1, occasional 0.2 with RL10x.

Take your powder measure apart, clean and degrease everything, inside and out. Dry it off thoroughly. Then stuff the hopper full of used dryer sheets, and let it sit overnight. Then, run a pound of powder through it a few times. If you're in a rust-prone area, you can coat the metal parts with wax, but it needs to be a hard, non-sticky wax so powder will flow freely.

Posted: 1/15/2019 10:38:18 PM EDT

[#8]

Quote History

Quoted:

That seems bad. RL15 is about the same grain length as RL10x, right? I get roughly 0.1, occasional 0.2 with RL10x.

Take your powder measure apart, clean and degrease everything, inside and out. Dry it off thoroughly. Then stuff the hopper full of used dryer sheets, and let it sit overnight. Then, run a pound of powder through it a few times. If you're in a rust-prone area, you can coat the metal parts with wax, but it needs to be a hard, non-sticky wax so powder will flow freely.

View Quote

Much easier to wax the inside of the PM instead of all that.

Covered in the second link I posted above.

Eta, my Redding PM throws Re 15 + or - .15 gr. With a 26.5 gr charge, that's not much.

I'm using proper technique and a tuned PM with a baffle.

Posted: 1/16/2019 3:02:17 AM EDT

[#9]

Already a lot of good info on prepping and technique with Uniflow style powder measures. Your variance does seem too large and probably would be addressed by methods mentioned.

I'll mention what I do. I don't usually use my Uniflow for extruded powders like R15. I was shocked to find the Lee Auto Drum to meter extruded powders more precisely.

I mainly use my Uniflow for ball and similar powders for which it is extremely precise...H110, etc.

I still polished and smoothed out the Lee unit and those cheap looking plastic drums. They look downright cheesy, but they work.

Some units are probably just better at one style powder or another.

Posted: 1/16/2019 3:37:04 AM EDT

[#10]

I'm getting about .2gr with RL-15 but I'm using the small drum. I in fact use the small drum for anything it's capable of charging.

I've even seen where people are using the small drum for higher capacity casings and setting it up to throw half of the charge and stroking it twice.

Of course this isn't necessary with ball powder. It's consistent all the time with either drum unless you are trying to throw very small charges with the large drum.

dryflash3 and some others on here have a good "tuning" method for those types of dispensers. If one of them hasn't described it on this thread maybe they will.

Motor

Posted: 1/16/2019 9:05:15 AM EDT

[#11]

Quote History

Quoted:
I'm getting about .2gr with RL-15 but I'm using the small drum. I in fact use the small drum for anything it's capable of charging.

I've even seen where people are using the small drum for higher capacity casings and setting it up to throw half of the charge and stroking it twice.

Of course this isn't necessary with ball powder. It's consistent all the time with either drum unless you are trying to throw very small charges with the large drum.

dryflash3 and some others on here have a good "tuning" method for those types of dispensers. If one of them hasn't described it on this thread maybe they will.

Motor

View Quote

My first post in this thread had 2 links with that info.

Posted: 1/16/2019 8:31:10 PM EDT

[#12]

Ok. I put in a homemade baffle and I paid extra attention to being consistent. I am staying mostly within .1 grain with the occasional .2 grain.

I am cycling the meter with a firm bump at both the upstroke and the down stroke while trying to keep my cadence as consistent as I can.

thanks

Posted: 1/16/2019 8:37:31 PM EDT

[#13]

One question that I haven't seen asked, or answered, what size drum are you using?

The Uniflow has 2, a large (11/16") and small (1/2").

The small is much more accurate, with less surface area at the opening.

Posted: 1/16/2019 8:50:37 PM EDT

[#14]

Quote History

Quoted:
I'm getting about .2gr with RL-15 but I'm using the small drum. I in fact use the small drum for anything it's capable of charging.

I've even seen where people are using the small drum for higher capacity casings and setting it up to throw half of the charge and stroking it twice.

Of course this isn't necessary with ball powder. It's consistent all the time with either drum unless you are trying to throw very small charges with the large drum.

dryflash3 and some others on here have a good "tuning" method for those types of dispensers. If one of them hasn't described it on this thread maybe they will.

Motor

View Quote

I too only use the small drum for everything up to .308 and 30.06. I thought about adding the large drum for rifle but I have not needed anything bigger. I would think the small drum would be more precise for the same given loads.

Posted: 1/16/2019 9:23:13 PM EDT

[#15]

When using the smaller measuring cylinder for large charges with this type of measure, you have to also pause a beat at the bottom of the lever's throw so that the powder can fully flow out of the metering cavity.

I think RCBS says the smaller cylinder is good up to 50 grains, but they never say with what powder. From a tolerance standpoint, I like to stay away from the ends of a measurement range, so I wouldn't use the small rotor for more than about 45 grains of ball powder.

Posted: 1/17/2019 12:26:21 AM EDT

[#16]

Quote History

Quoted:
Ok. I put in a homemade baffle and I paid extra attention to being consistent. I am staying mostly within .1 grain with the occasional .2 grain.

I am cycling the meter with a firm bump at both the upstroke and the down stroke while trying to keep my cadence as consistent as I can.

thanks

View Quote

Be sure to settle the powder before throwing charges you are going to weigh.

My standards are,

Ball powder, exact charges.

Flake powder, + or - .1 gr.

Short grain extruded, + or - .15 gr.

Keep at it and practice, I've been doing it awhile.

[ARCHIVED THREAD] - Question about RCBS Uniflow powder measure

Armory » Reloading

Warning

Confirm Action

About AR15.COM

Stay Connected

Newsletter

Contact Us