Powder Trickling Through Drop Tube

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  • Last Post 01 November 2023
Aaron posted this 31 October 2023

So let me ask a stupid question here. I have read that for the most accurate BPCR loads, one should use a powder drop tube to get more powder into a case. If I trickle in 90gr of FFG powder into a 45-90 case through a drop tube, and then compress the powder with a compression plug to a depth of .30" from the case mouth, why not just put 90 gr in there and compress it. It seems the drop tube is pointless if powder compression is used after it.

90 grains is 90 grains. I have gained nothing by using a drop tube. Yet, there are those who swear by a drop tube even when compressing. Comments?

 

 

With rifle in hand, I confidently go forth into the darkness.

trickle compression powder-compression

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RicinYakima posted this 31 October 2023

The theory is that the grains align better down the drop tube. When it is then compressed, fewer grains are broken for a more consistent burn. What I have read and what I have been told, it makes a difference at 600 yards plus. FWIW

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OU812 posted this 31 October 2023

I wonder who discovered the drop tube method? Good stuff

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Larry Gibson posted this 31 October 2023

I regularly load 70 gr (by weight) of FFFG or Cartridge BP in 45-70 cases for use under 405 or 500 gr bullets for use in my TDs. I used to use a drop tube as it was recommended and then a compression die.  I also just dropped the charge into the cases and then used a compression die.  After extensive testing I've found no difference in velocity, pressure or accuracy, even at 600 yards, between the two methods.  Hence, I no longer use the drop tube.

LMG

Concealment is not cover.........

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Aaron posted this 31 October 2023

Richard, this seems to make sense if very slight compression is used, better yet, no compression.

With rifle in hand, I confidently go forth into the darkness.

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Aaron posted this 31 October 2023

I'm with ya Larry. When I fill a 45-90 case to the top with 90gr of powder and then compress the poo out of it down to .30" below case mouth, it seems to me all "granular alignment" is moot. Below is the 45-90 with the PPB Lee 405 gr. Sized to .451 then patched. O.A.L. is 3.087" for the 1886 rifle.

 

 

With rifle in hand, I confidently go forth into the darkness.

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delmarskid posted this 31 October 2023

I know when I’ve pulled 45-70 black powder bullets I had compressed I had to dig the powder out with a screw driver. I often wonder why I picked a certain grade of powder when I basically crushed it into a big pill.

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RicinYakima posted this 01 November 2023

What you see as a big pill of powder, is not what the powder sees as it burns! There are 50,000 molecules of gas, standing side by side, for every 0.001" of space. 

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Bud Hyett posted this 01 November 2023

I often wonder why I picked a certain grade of powder when I basically crushed it into a big pill.

The British .450-.577 cartridge uses 85 grains of loose powder to obtain the same velocity as the .US .45-70 using 70 grains of compressed powder. 

Farm boy from Illinois, living in the magical Pacific Northwest

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RicinYakima posted this 01 November 2023

Black powder is not progressive, burns faster with more pressure, like smokeless. As the flame front moves through, the chemistry happens only with regard to surface area of the powder. FWIW

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Tom Acheson posted this 01 November 2023

I've used a drop tube ever since I started using black powder, 2009. Why? Because that's what everyone else did.....sorry John Alexander!


After reading the OP, I went to the loading room, weighed out 69-grains of Old Eynsford 1 1/2 black powder and poured it through a short plastic funnel into one of my 40 2 1/2 (.40-70 SS) cases. A small collection of powder granules spilled over the edge of the case mouth.

Not knowing the detailed reason to use a drop tube, one answer might be to make sure all powder ends up in the case? The theory on better aligning the granules might have value. However, a lot of people who load BP use a compression die. There have been many commentaries comparing different levels of powder compression and the impact on accuracy....out to 500-meters. A lot of those experiments were quite thorough. So everyone applies a different, but some, degree of powder compression. But it SEEMS that the effort to align granules, if that's the only reason, through a drop tube, might be cancelled out if the powder is compressed afterwards.

Tom

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Aaron posted this 01 November 2023

Agree Tom. Before compression became popular, one could get more granules per volume to a specific level in the case. With compression plugs, we can get even more in there with differing results.

I used to tap my cases to settle the powder down before seating a bullet to the powder level. Then I discovered the compression plug if more powder is desired.

With rifle in hand, I confidently go forth into the darkness.

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Aaron posted this 01 November 2023

It’s called “Flame Speed” and is the reason GOEX powder is used in US military munitions and shells. The BP aids consistent and faster ignition of the propellant it is mixed with. The US military is the largest consumer (customer) of GOEX powder.

With rifle in hand, I confidently go forth into the darkness.

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OU812 posted this 01 November 2023

I used drop tube, then compressed with die and Walter's wad, lubed big 500gr RCBS bullet with SPG, seated bullet. Clean barrel between each shot for best accuracy, blow tube did not work as well.

To help keep things more simple, I wonder how well TiteGroup powder would work in the 45/70 and big 500 gr bullet. What is a good smokeless load that simulates black powder velocities and requires no cleaning between shots?

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Aaron posted this 01 November 2023

I will caution you against the use of TiteGrp propellant in the 45-70 and other large cases with heavy bullets. You are apt to experience the phenomena called “detonation.”

Use Buffalo Rifle or Accurate 5744 for smokeless loads with large heavy bullets. The Accurate or Shooters World manuals have loads listed in them.

With rifle in hand, I confidently go forth into the darkness.

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Larry Gibson posted this 01 November 2023

Smokeless powders in cartridges do not "detonate", they burn progressively.....some are just faster burning than others.  The actual reason for S.E.E. or "high pressure excursions/event" are well known and documented and can easily be replicated.  "Detonation" is not one of the reasons and while originally theorized as a cause it has been disproven.  

LMG

Concealment is not cover.........

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Tom Acheson posted this 01 November 2023

Agree with Aaron on the caution about using a small charge of a very fast burning powder behind a very large heavy bullet in a cavernous case. That's an experiment I would never attempt! But I would use Tite Group in my much smaller .22 BR cases with an 80-grain bullet.

While out shooting my Model 74 Sharps with black powder, I discovered early on that after the first 1-2 shots a new round could not be chambered, due the accumulated powder residue in the throat area. The cure is to either use a blow tube between shots OR run two wet patches and one dry patch down the barrel. The latter is said to produce a similar bore condition for each shot. Sometimes the ambient relative humidity influences which conditioning approach to use.

A duplex load solves that chambering problem but some match rules prohibit the use of duplex loads. Duplex is putting a small amount of smokeless powder into the case and then adding the black powder. 4759 is/was a popular smokeless choice for that use. Supposedly the smokeless burns out the BP chamber residue.

If you visit the Shilo Rifle forum and do a search on smokeless loads, you'll find a lot of smokeless (and duplex) loads to consider. However, some BP shooters are adament traditionalists about using only BP in their rifles. And some of that is driven by the match rules of either NRA rifle silhouette or BP 1,000-yard target matches.

Tom

 

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Aaron posted this 01 November 2023

Larry, thanks for the contribution. As you have pointed out, a "pressure excursion" AKA detonation, is a very real event and can be duplicated. Suffice it to say, for the assistance of user OU812, that TiteGroup is NOT a propellant to be used in a 45-70 case with a 500gr bullet since it will most likely cause a pressure excursion, AKA detonation, in the cartridge due to "out of phase" pressure waves.

Lay ballistics folks use the term "Detonation", and therefore I used it in this context rather than attempting to describe a very complex pressure anomaly which may occur.  And yes, while it can be reproduced, its exact cause is unproven. Reflected and impacting (colliding) out of phase pressure waves are the primary theory with the folks I discuss this with. I agree with that theory. But....it's only theory until we can get little tiny guys inside of a cartridge. :-)

I'd love to hear your opinion on this but perhaps we should move that discussion to another channel since it is off topic here and has no bearing on drop tubes and powder compression.

 

 

With rifle in hand, I confidently go forth into the darkness.

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