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So here is where I ended up with my large stick/flake powder version. Working perfectly. I threw about 200 556 powder charges last night. variation in weight at about +/- a tenth of a grain variance. I was testing every 7-10 loads. Sometimes I was at (Ball powder) 27.5 grains, sometimes 27.6. This is using my RCBS 10-10 scale.
https://i.imgur.com/xJtj3e6.jpg
I dump the load with the same technique each time. Bring the measure up, give it a two count, bring it down, wait for a two count, and use the knocker twice.
I'm not super picky. If this is the best resolution I can expect with the 55, great, if not, is there any other tricks I should try?
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I think on your first try if you moved the choke point down closer to the bottom and used a different angle on the bottom inside and reduce or eliminate the straight section it might work also.
You don't really need any straight section between the upper taper and the bottom taper. The bottom taper only needs to be deep enough so the case mouth can set snug up to it.
This long upper taper will not crowd the powder together as quickly and should let the powder come together easier to pass out the bottom and into the case neck.
Looking at the drop tubes I have they are shaped that way inside.
Leo
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Dimner,
I’m trying to figure out why you are putting in more of a choke point... maybe I didn’t make my meaning clear(?) Any narrow portion in the overall path of the powder through the tube gives it the potential for a slowing or stoppage, what some writers refer to as “bridging” of the flakes or kernels. While opening up your upper chamber allows the powder to start its downward path quickly, putting that long narrow section in negates any advantage you gained. In fact, I would hypothesize that the big upper chamber would actually provide sufficient pre-loading to make that long, narrow neck an enhanced choke point that would encourage blockages. It’s a matter of scale though and the grain size will determine how significant this effect will be.
As for a drop consistency of +/- 0.1 gr on a 27.5 grain charge is a range of 0.36%, is that precise enough? Actually, you’re probably also bumping up against the limits of accuracy of your scale. You may be hitting weights of 27.52 and 27.58 and having it show up as 0.1 grains different! I wouldn’t worry about it.
Of course the bottom line will be on the range when you see how your loads do. Whether you are checking with a chronograph for deviations in velocity (SD) or group size on the target, this will ultimately tell you whether you’ve improved anything or not.
Froggie
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Good points about the choke point. My reason for the extended area was to get more of a "drop tube" like action with the device. What I mean by that is trying to restrain the rate of fill into the cartridge. That way it will fill the case more efficiently with extruded powders.
I'm probably using all the wrong terms here. But here is an example. When I am loading H4895 for my CMP Highpower loads or coyote loads for my CZ 527, my pet load fills the case up very close to 100%. Sometimes it looks like when I am about to seat a bullet, that the bullet will compress the powder. But if I cover the myth of the cartridge and tap the base of the cartridge on my desk, the powder settles a bit and lowers. Then there is no compression when seating the bullet.
I probably can achieve the same thing if I just remove most of the choke point tunnel and extend the upper funnel to take its place.
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It seems to my non-engineer mind that a long taper from the measure to the cartridge mouth would be the best. And you are not limited by length with your printer.
Ken
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Oh also....it's a balance scale. The 10-10, so the pointer on the scale is telling me that they are different weights. As I figured 0.01 grains isn't that bad.
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I have the best results with my 55 when I knock once with the lever up to settle the powder in the chamber and once with the lever down to make sure it all drops .
With your new drop tubes I would weigh a bunch and experiment with the powders you use and see what works best.
But the results you posted aren't bad at all. I often get better but + or - a tenth is acceptable to me , if I want perfect I trickle every charge.
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As I recall reading when the 222 was a popular bench rest cartridge they used a very long drop tube when loading 4198.
A short tube the powder flowed slower when it reached the case and powder could over flow the case.
Using a long drop tube of 12" the powder was moving faster when it entered the case, thus compacting the powder, no over flow.
I don't know how to use computer art work type programs so I can't draw a picture of what I meant.
On the bottom of the tube the taper can be about 45*. The top would taper all the way from the top down into the bottom taper leaving a hole just a bit smaller than your case mouth.
If you picture in your mind how the measure dumps the powder out of the measuring chamber, long tubular kernels are every which way. Some point down other sideways. Now as the kernels hit the taper in the drop tub those pointing down flow well. Those sideways one end will hit the side of the tube. A short taper the kernels won't have time enough change position to point down before they hit the choke point.
The longer the taper the more time the kernels have to move to pointing down.
Most measures have a tube length that the manufacturers feel will work well enough for most loading. Those who need something more are in the minority and these people don't create enough sales for the larger companies to make such a product. A lot of the people that need such tooling make their own or find someone who makes them.
As I mentioned MTM's funnel, it has a drop tube that is about 4" long. It has 4 tips that fit in this long drop tube for different size cases.
When I have a powder charge that fills a case full enough so I think it will cause bullet seating issues I use this long drop tube.
Leo
