Show me your BPCR drop tubes!

[Lead pot]

Brent I found this one at Scheels down the road from you.

Attachment 239747

My drop tubes are nothing fancy, Just a funnel on one end of a 3/8"OD (1/4" ID) type K copper tube with a 5/8" OD x 3/8" OD sweat reducer on the other end.

Attachment 239746

I just set the sweat reducer on the case and trickle the powder from the powder pan into the funnel and tap the funnel with the powder pan to make sure the powder did not bridge.

Attachment 239748

Kurt

[country gent]

My last drop tube was 3' of 3/8 od brass tubing. I used a 270 WSM case with the head cut off. Epoxied it on but you could use a 4' length of 1/4" threaded rod and bolt it in place and then solder it. Neck sets into case and shoulder is just over 1/2 dia so it centers the case nicely. A little work with a case trimmer you can remove most of the short neck pretty quickly

[rfd]

anti gravity drag from a spiral tube will slow the bp grain velocity. you want the bp to free fall from the full effect of gravity. a bp drop tube is actually an aiming device, no more or less.

[BrentD]

I inadvertently got my thumb into the torch flame for just a second while trying to get some solder into the crimped end when the tube turned and I reached for it. Ouch bigly.

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Good luck!

8

[Carrier]

Brent I found this one at Scheels down the road from you.

Attachment 239747

My drop tubes are nothing fancy, Just a funnel on one end of a 3/8"OD (1/4" ID) type K copper tube with a 5/8" OD x 3/8" OD sweat reducer on the other end.

Attachment 239746

I just set the sweat reducer on the case and trickle the powder from the powder pan into the funnel and tap the funnel with the powder pan to make sure the powder did not bridge.

Attachment 239748

Kurt

That looks just like the one I made.

[mazo kid]

You can get small brass funnels quite reasonably from Cash Mfg. Co.
http://www.tdcmfgstore.com/agora.cgi

[rfd]

You can get small brass funnels quite reasonably from Cash Mfg. Co.
http://www.tdcmfgstore.com/agora.cgi

the largest i'd seen at their site is 1-1/2" diameter - too small.

[mazo kid]

Depends on your point of view. I find that size quite adequate as I pour the charge very slowly into the funnel, from either a dipper, adjustable powder measure, or the powder scale cup. I don't have a TDC funnel, but my home-made one is about that size.

[rfd]

1-1/2" diameter funnel bell can allow bp grains to hop out during the trickle down. also, i want a funnel that has some height so as the grains bop the funnel side, they're headed down to the funnel's end. got an alum one years ago in the sorta town general store for about $4, i believe. 2-3/4" inside the top bell. epoxied to a 29" alum arrow shaft.

[mazo kid]

I can see where the deeper sides would be easier to use. I have a couple of aluminum arrow shafts, will have to see about finding (or making) another funnel about that size.

[indian joe]

I can see where the deeper sides would be easier to use. I have a couple of aluminum arrow shafts, will have to see about finding (or making) a funnel about that size.

When you are setting it up run a cleaning brush dipped in powdered graphite end to end down the tube - helps heaps to stop bridging and speed up the flow.

[mazo kid]

When you are setting it up run a cleaning brush dipped in powdered graphite end to end down the tube - helps heaps to stop bridging and speed up the flow.

And gets rid of spiderwebs! The funnel I made has steeply sloping sides so helps keep the powder going down. I also just found a set of 3 different sized stainless funnels, largest one is close to 3" diameter. Found them on eBay for $4.00 for the set. Of course I'll have to wait a couple of weeks for them to come from China, but I'm in no hurry.

[country gent]

When I make a drop tube I polish the inside of the tube with 800 up to 1500 grit paper flaps then flitz or simichrome on soft flannel. This gives a mirror smooth finish and removes burrs and smooths rough areas from the extrusion process. only takes a couple passes with each grit and a few mins with the polish.

Funnels can be turned up but its a lot of wasted metals doing so. With a little layout and forming one can be bent formed from sheet stock that does the job.
Set a divider to 1 1/2" to 1 3/4" ( this is actually 3-3 1/2) draw an arc on paper then set the divider to 1/2 of tube dia and draw a second arc using the same center both 180* connect ends of arcs and match edges together f this is what you want you have the template for your funnel in shim stock of brass aluminum steel or plastic. Add a 1/4" to each edge for a fold over lap joint form and fit joint solder.

[mazo kid]

That's about how I made my funnel. Good idea about polishing the interior of the drop tube, I can still do that to mine.

[rfd]

after a few hundred drops of bp the funnel and tube interiors will be nicely graphite coated - no need for polishing.