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Old February 24, 2002, 04:11 PM   #1
renaissance7697
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Consistency in throwing powder

I have been working for years now with a RCBS Piggyback II mounted on a Rockchucker and a RCBS "Uniflow" powter dispenser.
I measure my charges with a RCBS 10/10 scale

I recently got RCBS's "Micrometer Screw" attachment for the
Uniflow. This give a calibrated charge adjustment metering capability.
In getting aquainted with the Micrometer Screw, I noticed something, that I do not remember experiencing with the old
screw device.

I will set the measure so that it seems to give the desired powder drop, then throw at least 4 charges that average out to my desired charge before locking in the screw.

Checking (by weighing) my charge every 10 or so throws, I find that the average weight thrown, drifts.

For an example; if I think I am set up for 4.0 grains, after 10, 20 throws, I find that I have drifted to 4.2 or 4.3 .
(In this example I am using Hodgdon > CLAYS CLAYS

After that, it seems to HOLD at the new weight.

Why does it take 30 or so throws to "settle in" ?

Am I expecting too much accuracy for the equipment I am using.
.2 or .3 grains drift, starting at 4.0 is about 5 %.

What should I be able to reasonably expect?

I do concentrate on all the recommended techniques ( ie consistency in motion etc and etc)

I DO NOT have a powder baffel (sp?).
Could this make this much of a difference?
I always try to keep my hopper at least 1/3 full.

Is my new micrometer screw drifting as it settles in ?

What can one reasonably expect ?
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Old February 24, 2002, 04:47 PM   #2
sebago
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I think your problem is being caused by the powder settling and compacting due to the vibration of the powder measure being operated. If the powder kernels are closer together then more would be able to fit into a certain size cavity. I think a powder baffle is just what you need, either that or throw however many charges it takes to get consistant weights.
I hope this helps, sebago.
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Old February 24, 2002, 06:16 PM   #3
renaissance7697
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For Sebago

What you say makes total sense.
I'm going to get (make?) one.
Thank you!
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Old February 25, 2002, 12:51 AM   #4
Bill Adair
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Renaissance7697,

Some instruction manuals tell you to throw at least 30 charges back into the hopper, before starting a reloading session, as it takes approximately that long to settle the powder in the hopper.

I go one step farther, and rap on the measure until I can see no more settling in the hopper, and then throw the settling charges.

A baffle seems to help with some powders, but you will still need to get the powder settled first.

I think it is natural for the thrown charge to drift during long loading sessions, because the powder gradually sifts the finer grains toward the bottom of the hopper, while the coarser grains tend to migrate upward. Typically, I've seen no more than a tenth of a grain variation that I could attribute to this, once the powder is settled. Hardly enough to worry about, as you won't see that at the target.

Bill
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Old February 25, 2002, 11:44 AM   #5
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Good information, here. I would only add that you should make SURE that the metering insert is clean and dry inside. When they are shipped, they might have some anit-rust gunk on them and that can cause the powder to stick inside the insert and cause the throws to be inconsistant. Hornady's One Shot Dry Lube and Gun Cleaner (I think that's what it's called) is excellent for this.

Good luck,

Jim
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Old February 25, 2002, 12:22 PM   #6
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Good information, here. I would only add that you should make SURE that the metering insert is clean and dry inside. When they are shipped, they might have some anit-rust gunk on them and that can cause the powder to stick inside the insert and cause the throws to be inconsistant. Hornady's One Shot Dry Lube and Gun Cleaner (I think that's what it's called) is excellent for this.

Good luck,

Jim
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Old February 25, 2002, 01:23 PM   #7
renaissance7697
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Resolution of Problem

Tried all suggestions.

Made a baffel but it did not help.

Turned out the settling of the powder in the hopper was the key.

With the old Piggyback case activated powder drop,
there was not much agitation of the powder measure.

When I recently switched to the NEW case activated powder
drop device > there was a LOT of shaking down because the powder measure rises and then DROPS hard when dolling out the powder.
Totally different action > behaves differently.

PROOF:

I filled the measure and then immeadiately (without attempting to settle the powder) > set the charge for 4.0
Got four consecutive drops ~= > 4.0
Then, I shook down the powder By simulating the case activated drop triggering action 30 or so times without dropping any powder
Threw another charge, and it was 4.2
Charge HELD at 4.2 from then on

I emptied and refilled the hopper.
Shook down the powder By simulating the drop hard action 30 or so times BEFORE setting the merering device.
Set the metering device to drop 4.0
It DID drop 4.0
And held steady at 4.0 for the next 100 drops.

Problem understood
Problem solved.

Thanks guys!
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Old February 25, 2002, 02:55 PM   #8
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I'd recommend that you give Sinclair a call, and order their bottle adapter - It'll let you put a larger powder hopper on top of the thing, so you won't have to work as hard to keep it topped off...
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Old February 25, 2002, 04:24 PM   #9
zot
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I have the piggy 2 setup, powder checker die included, but after
200 rds I found a ball of HS-6 blocking my charge, 200 squib loads
static I guess, poped the ball with a pencil,and the powder checker die didn't show I was light, it was gumed up with fine
powder, dust. I guess I learned clean the whole machine after a few 100 rds, I hate how powder falls under shell plate, also those dang primer springs flying off into space every once in awhile, learned to tie a thread to springs, never find em once they fly.
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