RCBS powder throw consistency

[Wulfgar85]

Hi folks,
I recently bought a new-to-me RCBS uniflow powder measure. I’m having a really hard time getting consistent charges with it. Seems to be off up to .3-.7 grains any given time. I’m trying to be consistent in how I operate the handle - 1 knock at top, 1 knock at bottom - but can’t seem to get to where I trust it to give me a decent charge. I’ve tried it with IMR 4064, CFE223, and H4350 with charges anywhere from 30 to 60 grains. I weighing the charges from it on a Lee powder safety scale and a franklin arsenal electronic one to. Anyone had any experience with this and maybe some tips?

thanks

 

[Robert Richardson]

Wow, my Uni-Flow will drop CFE223 power and just about all ball type power with-in a tenth of a grain.

 

[billybob44]

Hi folks,
I recently bought a new-to-me RCBS uniflow powder measure. I’m having a really hard time getting consistent charges with it. Seems to be off up to .3-.7 grains any given time. I’m trying to be consistent in how I operate the handle - 1 knock at top, 1 knock at bottom - but can’t seem to get to where I trust it to give me a decent charge. I’ve tried it with IMR 4064, CFE223, and H4350 with charges anywhere from 30 to 60 grains. I weighing the charges from it on a Lee powder safety scale and a franklin arsenal electronic one to. Anyone had any experience with this and maybe some tips?

thanks

CFE223 really should be closer?? Most ball powder is.
For most loads, be SURE to use the Uniflow SMALL powder drum. This drum is quite a bit smaller in diameter (Charge hole) and will throw more accurate charges, up to around 30-35 grain charges...Bill.

 

[billybob44]

I guess it would help to know what caliber that you are loading for?? and what bullet??..Bill.

 

[Wulfgar85]

Sure, I’m loading 224 Valkyrie, 30-06, and 6.5x55 swede. 90 gr in the Valkyrie, 150-165 interlocks in the 30-06, and 130 vlds and 140 sst in the 6.5. So I’m mostly concerned with rifle powder. 40-60 grains of powder. Haven’t hardly got going though cuz I haven’t got this powder measure sorted out.

 

[Wulfgar85]

CFE223 really should be closer?? Most ball powder is.
For most loads, be SURE to use the Uniflow SMALL powder drum. This drum is quite a bit smaller in diameter (Charge hole) and will throw more accurate charges, up to around 30-35 grain charges...Bill.

Would the small powder drum work for the 40-55 grain charges?

 

[Indy574]

When you say one knock at the top and one knock at the bottom, what are you referring too? If you are tapping it with another instrument then this could be the issue.
I would pause for a second once you hit the top and then bring the handle back down to the stop. No additional tapping is necessary unless at the bottom for stick powders. I’ve had them hang up before.
You may want to disassemble and clean it as well.

 

[Wulfgar85]

When you say one knock at the top and one knock at the bottom, what are you referring too? If you are tapping it with another instrument then this could be the issue.
I would pause for a second once you hit the top and then bring the handle back down to the stop. No additional tapping is necessary unless at the bottom for stick powders. I’ve had them hang up before.
You may want to disassemble and clean it as well.

At the top and bottom of the throws travel I let the handle tap against the stop. I’ll try giving her a good clean too

 

[billybob44]

Would the small powder drum work for the 40-55 grain charges?

Probably not. But you may?? have more accuracy with 2-20gr. dumps for a 40gr. charge=2-25gr. for 50gr. etc??
The uniflow is known for mostly accurate charges, unless you want to spend 4-5X the $$$..

PS: You will find that with 35+gr. charges of powder in a case that .3-.5gr. difference in charge weights will affect your long range groups little. Other things will make more differences in your groups...Bill.

 

[Wulfgar85]

PS: You will find that with 35+gr. charges of powder in a case that .3-.5gr. difference in charge weights will affect your long range groups little. Other things will make more differences in your groups...Bill.

this bit was also something I was wondering. Thank you

 

[NKBJ]

If you find that your equipment doesn't produce the level of precision that you're after then implement an additional processing step, weighing the charges and adding as necessary. Otherwise what you're sure of is that the loads are not within the tolerances you previously set to be achieved.

 

[rhslover]

Since it's new, is it possible there's some lube in it? Might try taking it apart and cleaning it.

 

[Hawkeye7br]

Wow, my Uni-Flow will drop CFE223 power and just about all ball type power with-in a tenth of a grain.

Ditto for mine.
I too tap the handle at the top of the stroke when the cylinder is emptying. It isn't to assist emptying, it's to make sure stick powders aren't hung up on the much smaller diameter tube that channels the powder into the case mouth. The extra time also ensures the I'm not running the dump lever before it totally empties.

 

[tsm]

Since it's new, is it possible there's some lube in it? Might try taking it apart and cleaning it.

Ditto on the cleaning recommendation. RCBS specifies how to initially clean their measures and it’s pretty easy to do. Hopefully the OP resolved his issue since the thread began about 3 weeks ago.

 

[Hawkeye7br]

I leave a funnel in the top of the powder hopper, the bottom of it extends about halfway into the hopper. I pour in powder until it backs up into the funnel, and keep powder in the funnel as I load. I do this to simulate the effect of the internal baffle found on expensive powder throwers. The baffle (or my funnel) maintains a consistent level and weight for the powder in the hopper. I figure if some engineer determined full hoppers weigh powder different from almost empty hoppers...that's good enough for me.

 

[NKBJ]

I leave a funnel in the top of the powder hopper, the bottom of it extends about halfway into the hopper. I pour in powder until it backs up into the funnel, and keep powder in the funnel as I load. I do this to simulate the effect of the internal baffle found on expensive powder throwers. The baffle (or my funnel) maintains a consistent level and weight for the powder in the hopper. I figure if some engineer determined full hoppers weigh powder different from almost empty hoppers...that's good enough for me.

Me too, exactly.

 

[wingrider1800]

I leave a funnel in the top of the powder hopper, the bottom of it extends about halfway into the hopper. I pour in powder until it backs up into the funnel, and keep powder in the funnel as I load. I do this to simulate the effect of the internal baffle found on expensive powder throwers. The baffle (or my funnel) maintains a consistent level and weight for the powder in the hopper. I figure if some engineer determined full hoppers weigh powder different from almost empty hoppers...that's good enough for me.

Never thought of that but it makes sense to me. My uniflow will usually stay within .1 grains, especially with ball powder.

 

[2in1evtime]

Sometimes static builds up and causes inconsistent throws