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Thread: Drop Tube Using Helically Coiled Tubing? Or Angled?

  1. #1
    Boolit Buddy
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    Drop Tube Using Helically Coiled Tubing? Or Angled?

    Has anyone ever tried using a drop tube that does not have a straight drop, but instead slows the flow of the powder into the case by using a coiled tube, or mounting a straight tube at an angle?

    One of the areas I feel I introduce variation in the loading process is when I trickle the charge into the case through a drop tube. If there were a way to get around the trickling part, like having a tube with a slope that would govern how fast the powder arrives at the case, then I wouldn't have to worry about it.

    Has this ever bothered anybody else?

  2. #2
    Boolit Master

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    I seem to remember reading about a writer doing this with pyrex tubing and a helical wrap around a mandrel in the 80s. He packed the tube with salt to keep it from crushing distorting. Heated in an oven and wrapped around a mandrell. He did it to try and alighn granuals of powder and have a longer tube at a shorter height. A 36" straight tube is tall and hard to use. A 36" piece of tube helically wrapped around a 1" mandrel may only stand 18-20" high. You would want to wrap at a 45* helix angle to maintain flow thru the tube. Any flater angle powder may stop bridge or jam.

    We would wrap cooper cooling coils in one shop by chucking a 4" pipe in the lathe and clamping the tubing to it had a rest similar to a wood lathe and ran at lowest rpms possible. One guy guided tube other ran the clutch. We made some nice looking coils but they were for cooling water or oil on machines. Granular material by gravity needs more fall to work.

    I believe that was the reason for the clear tubing so powder that stuck could be seen. What might work is to bend your helix on a heavy wire and use a piece of flexible tubing using wire rings to hold tubing every 2-3" along the length. Otherwise a mandrel made with a radiused groove at the helix angle and tubing wrapped around mandrel and in the groove.

  3. #3
    Boolit Master DonMountain's Avatar
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    I thought the drop tube length was to increase the velocity of the powder kernels so they jarred the surrounding powder into better and more compact shape, allowing more powder to fit in a case in a more dense arrangement. What you are suggesting is to negate this altogether, giving no more advantage than just dumping the powder directly into a case using a funnel.

  4. #4
    Boolit Buddy
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    Don: I had taken it for granted that I was supposed to trickle the powder into the funnel. Then the tube would somehow cause the powder to settle in the case. You Tube video using glass containers show the user's hand starting the powder real slow, so I thought slow was the watchword. If the purpose of the drop tube is to, as you say, "increase the velocity of the powder kernels", thereby settling them into a smaller volume, I have indeed misunderstood the process completely. Coiling the tube would be counterproductive. Now you have me wondering how to show what actually happens.

  5. #5
    Boolit Master
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    Purpose of any gravity drop tube: to settle the powder grains together. Only way to determine which type or length of a drop that is better - measure different heights of the powder columns in the case
    The other method to settle the powder grains in the powder column is to vibrate the case with the powder dropped loosely into it. I use this method and watch the powder column height shrink. Have compared column height differences between a 36" drop tube and vibrating the powder = No Difference. So I vibrate because it is quicker to settle the powder for say a 50 case tray
    Regards
    John

  6. #6
    Boolit Master
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    In my powder charging "style" I only use a drop tube for charging rifle cases, not for trickling up a charge. Any "trickling" I do is into the pan on my scale when getting an exact/consistent powder charge and dump the charge into a funnel/drop tube into the case...

    FWIW; Beware youtube reloading videos!
    My Anchor is holding fast!

  7. #7
    Boolit Buddy
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    mdi, I may have used a word ("trickle") in the generic sense, not the way a reloader would use it (as in "trickling" a powder charge), and I may have confused the issue. I just meant that the powder was administered to the funnel at the top of the drop tube very slowly and carefully. The You Tube video is from Svartkrutt.net, and is four years old, and shows plainly the difference between "slow and careful" and "dumped". My questions, after having read DonMountain's response, are 1) Has anyone here tested for what actually happens (I am sure there are many of you), and who therefore can with authority tell me that "slow and careful" is unnecessary? And 2) Do any of these tests confirm that there is a point beyond which no additional settlement of the powder occurs? I mean, I will buy, or fashion, a ten foot long drop tube if I must, but I bet a shorter one will get me to the same point.

  8. #8
    Boolit Master
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    Those with more experience than me, especially with black powder cartridge reloading, can attest that one is able to get more powder in a cartridge by using a drop tube of sufficient length. I don't know/think speed of pour has much importance...

    Jes thinkin', if the powder charge is not compressed/fills the case, general handling, boxing, transporting, loading, etc, would "shake up" the powder charge anyway...
    Last edited by mdi; Yesterday at 03:44 PM.
    My Anchor is holding fast!

  9. #9
    Boolit Master DonMountain's Avatar
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    My guess is that with all things that are dropped through the air, they all reach a "terminal velocity" based on the density of the air and the size/shape/weight of the falling object. When people skydive they only reach about 120 miles per hour. And black powder kernels probably reach their "terminal velocity" in a 36" tube, as was determined by the ancient reloaders around the 1870's when cartridge reloading began in earnest. So, rather than reinventing the wheel, I just assumed that my great grandfather's drop tube was the length to use when trying to maximize the powder in my 45-70 black powder cartridges. I also think that the next best thing would be a gently vibrating case holder. But I would think that you would have to fill up the case just short of the neck, vibrate it, then fill it up again, and then vibrate it again, and then vibrate it and load your wad and projectile, compressing the load slightly. So, the straight drop tube seems easier and a one shot and done method.

  10. #10
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    Butler Ford's Avatar
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    As it was explained to me, a drop tube allows for getting more powder in the case without crushing the grains which will change the burn rate and is one of the reasons that black powder shooters can, with regularity, keep standard deviations in the single digits. It is my personal belief that it carries over to smokeless as well. I seem to have better luck using powders that give 100+% case fill and by using a drop tube, I can get the 103% in the case without compression.

    BF
    "The price good men pay for indifference to public affairs is to be ruled by evil men."--Plato

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check