RCBS Powder Thrower Test

[mram10]

I was loading for my edge(89.5gr H-1000) and decided to weigh every charge like i use to. I weighed 30 charges using a slight click at the bottom and medium paced movement upward on handle. I also played with 3 clicks at the bottom and tested what would happen when it caught on a grain.

- In 30 charges, 25 were between 89.2-89.7 with 5 of them going as high as 90.5.
- When doing 2-3 clicks at the bottom, the powder compressed enough to give charge weights of 91.5
- When using the large funnel with a spout that goes half way into the reservoir, the weights were within +/- .2 the majority of the time.
- When not using the funnel, the charges were +/- .5 most of the time. The extreme, up to 1 grain off.
- When catching on a grain and pushing through, it stayed within the normal parameters.

I unloaded the reservoir and loaded it again to see if it would be the same charge. The first throw was 91.7 and the next 15 were from 89.7-90.4.

I am sure most of you already know this, but I have not seem a post and wanted to help the amateurs like myself

note: all weights were weighed on a digital Pact BBK2 scale and it was verified with an RCBS beam scale every few charges when it seemed the weight was off more than expected.

 

[wiuprof]

What type of RCBS unit is this? Is it the Uniflow? Where and how is the "funnel" being used?

I have two Uniflows with "baffles" in them (one with large cylinder & another with the smaller one) but am wondering how you are using a "funnel" in the unit.

Thanks

 

[LHSmith]

I'd be concerned at the results when you attempted to repeat the test by emptying the reservoir, started over, and got higher numbers. I'd suspect a drifting electronic scale. The only other thing that causes a consistent change in readings ( assuming your technique was uniform) is adsorption of moisture through time, such a commonly found while reloading at the range.

 

[Bayou]

What RCBS product are you testing?

 

[Road_Clam]

I never trust any thrower for repeatable precision. If i'm just banging out some .223 training/plinking ammo then no problem just "throw-n-go" but when I need to precisely control my charges I throw about .2 under my target weight then trickle up. My Uniflow varies about .3 at worst. Sometimes I will see a perfect throw for 5 or so loads, then all of a sudden I get a variance.

 

[mram10]

I have a 4" diameter funnel that has a 4"spout that ends half way down my uniflow. I pour the powder into the funnel until it has filled both the reservoir and funnel. That keep uniform pressure during throws. It is the basic Uniflow thrower that comes with the rock chucker supreme kit.
As for drifting scale, unless my beam scale was drifting .... Try it for yourself. I just redid the experiment with the same result.

 

[LHSmith]

One thing I do to check a scale, balance beam or electronic, is to periodically weigh use check weights (of a weight close to your targeted drop charge during the loading process). I have had the Uniflow , a 505 beam scale (started with that set) and the BBK-2. I have since moved on to better equipment ( the BBK-2 lasted 1 week) and life has been much easier since I gained confidence in my powder measuring equipment. I also have learned to take the measure apart and clean the drums often. Invariably there is powder kernels, balls, flakes adhering to the inside surfaces of the measure.

 

[johara1]

I tried a Hornady, which is licensed copy of the RCBS on a progressive loader with 8208 and it was all over the place to the point of putting it back in the box. I weighed on a GD 503. I found it not capable of holding a full grain on the press. I also tried it manual and it wasn't much better…….. jim