Benefits of the drop tube.

[bobm]

I was surprised that 90 grs. of fine grain Hodgdon Benchmark responded well to drop tubing.

 

[JB10]

How well do they work on ball powders? I have a case with w748 that i tap on case to lower the powder. Accuracy is same wether i tap it down or just load a round. The carge is pretty full with the load i use

 

[dellet]

How well do they work on ball powders? I have a case with w748 that i tap on case to lower the powder. Accuracy is same wether i tap it down or just load a round. The carge is pretty full with the load i use

Ball powders load very well with a drop tube, maybe too well.
Fine ball powders stack very efficiently, like sand, enough so that any further compression becomes a question of whether the bullet deforms, or you get that last .005” of seating depth.

I will drop a charge in a fired case, then a bullet and measure seated depth. That way I know exactly where compression begins. You often can’t feel it start using a press with a lot of leverage.

 

[dcali]

Does compacting the powder with a drop tube change the burn rate?

I've never heard of such a thing and can't think of a reason it would. Don't crack up the granules, though. A large part of a powder's burn rate comes from its surface area - so don't go crunching them in with force to fit more in. That's a bad idea.

 

[big5ifty]

105 grains IMR 7977, and then through a drop tube the size of a large primer pickup tube

 

[butchlambert]

I threaded the inside of my 4" tube. Slow drop with H4198 in the 30BR will get 35 grains to less than half the neck.

 

[bobm]

How well do they work on ball powders? I have a case with w748 that i tap on case to lower the powder. Accuracy is same wether i tap it down or just load a round. The carge is pretty full with the load i use

I had no ball powder in my house. My neighbor gave me a sample of WW-760 for drop tube testing.

Yes indeed, ball propellant settles nicely with the drop tube method. Shown is 88.0 grs. loose dumped next to same amount dropped.

A dropped case full of 760 weighed 98.0 grs.

 

[D Coots]

I don't drop powder from a measure anymore. But when I did I had a piece of white paper taped to the back of my drop tube. You can control that surge of powder that way. Much easier to see.

 

[rayporter]

masking tape is better than nothing but it ages poorly.

white electrical tape it good at letting you see the powder in the drop tube.

 

[BoydAllen]

I've never heard of such a thing and can't think of a reason it would. Don't crack up the granules, though. A large part of a powder's burn rate comes from its surface area - so don't go crunching them in with force to fit more in. That's a bad idea.

Actually, in the past, I have shot loads that were so compressed that they pushed the bullet back out a little, with no ill effects. This was with an extruded powder, of medium burn rate. I am not saying to do this, or suggesting that anyone else do it, just reporting. Based on recent conversations, I believe that among .30 BR shooters, compressed loads are pretty common.

 

[dcali]

Actually, in the past, I have shot loads that were so compressed that they pushed the bullet back out a little, with no ill effects. This was with an extruded powder, of medium burn rate. I am not saying to do this, or suggesting that anyone else do it, just reporting. Based on recent conversations, I believe that among .30 BR shooters, compressed loads are pretty common.

Same here. One of the more annoying things about my .30BR is trying to fit all the powder in the case. I don't think compressing loads actually cracks the powder though - if so, not much. I'm just warning people not to get creative in trying to get more powder in.

 

[bobm]

Same here. One of the more annoying things about my .30BR is trying to fit all the powder in the case. I don't think compressing loads actually cracks the powder though - if so, not much. I'm just warning people not to get creative in trying to get more powder in.

Well, I put that theory to the test.

I took a fired, unsized 7mm-08 case and slow dropped tubed in RL-22 to the top. I pressed in a long shank 175gr. Hornady well past the cannelure and could have gone further. The propellant was simply breaking apart with no push back. The bullet got firmly stuck in the seating stem and acted as a pushing pin. About 20% of the forward powder charge was crushed. Zero bullet deformation in shape or diameter.

 

[dcali]

Well, I put that theory to the test.

I took a fired, unsized 7mm-08 case and slow dropped tubed in RL-22 to the top. I pressed in a long shank 175gr. Hornady well past the cannelure and could have gone further. The propellant was simply breaking apart with no push back. The bullet got firmly stuck in the seating stem and acted as a pushing pin. About 20% of the forward powder charge was crushed. Zero bullet deformation in shape or diameter.

Very interesting. I always assumed the crunch was things settling, and maybe a few bits cracking. That's a good bit more than I'd have guessed. In theory, that should bump the burn rate up a little on heavily compressed loads. I can't say i've ever paid close enough attention to notice.

Excellent work. It would be interesting use that powder (the cracked stuff) in a non-compressed load and compare it to unmolested powder and see if there's a measurable increase in velocity.

 

[big5ifty]

Excellent work. It would be interesting use that powder (the cracked stuff) in a non-compressed load and compare it to unmolested powder and see if there's a measurable increase in velocity.

The coating on powder is a burn retardant.

When you break the powder granules, you effectively un-coat them.

 

[Shinbone]

If you don't need a drop tube, your powder burns too fast.

 

[varget204]

Forget the drop tubes, get a Cheap electric toothbrush, Cut Off bristles, Vibrate base of case, only takes a few seconds

 

[D Coots]

masking tape is better than nothing but it ages poorly.

white electrical tape it good at letting you see the powder in the drop tube.

Ray. You can lead a horse to water......