Powder Bridging

[klw]

I've got five progressives, two RCBS Piggyback III's and three RCBS Pro 2000's. Like a lot of progressives these machines have a powder measure on top of a powder drop tube. Nothing unusual in that.

Today I was loading some 38-55 cartridges. I've done this hundreds of times just this year. But something was odd. A couple of the cases got very serious mouth deformation at the powder charging station. That just can not happen. There is nothing there that could cause that.

So I took the machine apart. The powder drop tube had well over 100 grains of Unique in it. That is at least ten 38-55 cartridge's worth of powder. I've started disassembling my 38-55 cartridges. So far I have not found one with a powder charge in it.

In this progressive there is what is called a "large rifle powder funnel" in the powder drop tube. Actually it isn't all that big a piece. There are three possible powder funnels, one for pistols, one for small rifles and one for large rifles. The funnel moves up and down inside the drop tube. This is how the falling powder charge is aimed into the case mouth. Up until today this has worked perfectly. Probably loaded over 100,000 on these machines without any problems.

Actually at least once when a year's shooting was over and I took these machine apart I found that I had put the funnel in upside down. Still worked. I also found once that I had put two funnels in one machine. Didn't cause any problems.

But this funnel was perfect. Clean. Inserted right side up. Nothing wrong.

But the powder bridged. By bridging I mean that it plugged up or bridged over the opening in the large rifle powder funnel. Unique just doesn't do that. Well at least not until today.

Why this happened is beyond me. The machine was put together properly. There wasn't grease, oil or anything else where it shouldn't have been.

Of course if bridging had happened for awhile and then the bridge had broken I could have easily ended up with a double or triple charge in a case. That would have been bad.

RCBS makes a die that checks for powder height. But there is not enought die stations in these machines for me to use it here.

Any I've loaded tens of thousands of charges on these units. A lot of them were rifle rounds. Most used Unique.

But today things went wrong. Fortunately I caught this before killing myself but that was just the grace of God.

This worries me AND I don't know how to prevent it from happening again.

[Lloyd Smale]

good you caught it. Any chance your powder had gotten damp.

[SharpsShooter]

A good friend of mine loaded 500 or so 45lc with a Lyman 55 measure using Unique. Long story short, I ended up with the ammo as part of a trade. The first 12 or 18 rounds were interesting to say the least and I started calling it "surprise surprise" brand. He is a very safety concious reloader and apparently he had a bridging problem also, but did not discover it before the ammo changed hands. It was nothing dramatic, just the occasional "pop" "bang" "kaboom" differences in load. He took the ammo back, pulled all the bullets and sold the 55. I've always suspected it was moisture in the drop tube, but never had the chance to mention it to him before he sold the measure. I use a 55 for BP and a Lee perfect measure for smokeless and have not had any problem.

I have heard that if you wipe the internal parts of the measure with a dryer sheet and push it through drop tube, it would reduce static bridging, but heve never needed to test the theory.

SS

[No_1]

I have a ammomaster and it comes with a clear adapter tube that is used to attach the powder measurer to the press. Theory is you can watch the powder drop. I am sure that in the heat of reloading while looking down to add brass and boolits it can be cumbersome to look up at the tube. Does yours have that clear tube?

R.

[klw]

During the winter I segregrate by weight all the various bullets I'm going to shoot in the coming year. This takes forever. But at least all the rounds have bullets which nominally are within one grain of each other.

I don't weigh my brass.

Today I took this tool apart, inspected every possible surface, cleaned everything and loaded a test round. A properly loaded cartridge weighs right at 401 grains.

So I went back and weighed the 100 rounds I have. All but 16 weighed right at 401 grains. I took a couple of these apart. They had a full charge. I took apart everything that weighted below 400 grains. As the weight of the cartridges dropped the weight of the powder charge dropped. At 394 grains or so there was virtually no powder in the case.

If you plot these low weights in the order of decreasing weight you can actually "see" I think the powder being choked off. That surprised me. It also surprised me that it was this easy to spot this problem by just weighing the cartridges. Oh I knew that there would be little or no weight variability in the bullet weights but for this to work there has to also be little or no weight variability in the brass and primer weight. That there is little or no weight variability in both the brass and primers is obviously true but I wouldn't have expected that.

Flagstaff Arizona is having a drought. Started the year we retired and moved here, 1997. The drought is suppose to last anywhere from 10 to 40 years. God help us because Flagstaff is right in the middle of the biggest pine forest in north america.

But every year we have heavy heavy rains just about now. So the humidity is up from almost nothing to noticeable.

Haven't used this press in about two weeks. Think that there must have been just a little powder dust in the drop tube. Pretty sure about that because I found it during the extensive cleaning this machine just got. Think that the charges thrown today started sticking on this dust and rather quickly choked off the drop tube. Makes sense but it is still odd.

The amount of dust I'm talking about isn't much. This machine shakes noticeably during use. I actually want that because it is a defense against bridging. Still the powder bridged.

I would have bet my life, literally, that this could not possibly have happened. Unique is not a good candidate for bridging. The machine bounds around during use (deliberately to minimize bridging). And yet it happened.

If this thing had bridged for awhile and then let go life could have had a real surprise in it.

Actually the downside isn't all that bad. I'm shooting this in a Lone Star Rolling block. Those guns are STRONG. Also between the volumn taken up by a normal charge and the volume taken up by deep seating the bullet the worst that could have happened would have been a double charge. I'm pretty sure that the gun could have handled that.

BUT Unique bridges. Didn't know that!

[44man]

I have it happen all the time with shot. Can't see anything except to look at each shell as it is turned from under the hopper.
It also happens with any powder measure and any powder. Just because the powder has small grains doesn't mean it can't bridge. Thats why when I throw charges I use a loading block and watch each charge come out of the tube. I then inspect every case before seating any boolits. Progressive presses scare me!
Moisture is not needed, just the way the powder falls. If it was poured slow, it would all come out but when dumped right into a funnel you don't know what will happen. I see it all the time with a big funnel in a can of powder when I empty my measure. I don't know how many times I have dumped powder on the bench because it never went through the funnel. I always look now.
Even when going from a scale pan into a powder funnel, half won't go through until I tap the funnel.
That's why some presses have a powder check, to make sure it is in the case.
There is only one solution, slow down, look at every case after charging. Mount a mirror and light so you can glance at the inside of each case.
A powder measure should have a vibrator that activates only when the powder is dumped.

[klw]

When I retired in 97 I had always meant to shoot a lot. But at 54 I hadn't done it yet. So in 2000 I started going shooting five days a week ten months out of the year. Shoot about 18,000 rounds a year.

When I was younger I collected reloading equipment. Probably had 60 presses including 36 different progressives. Sold all this stuff to a gun store in Albuquerque.

Having had a chance to use just about every complicated hand operated reloader I picked the two mentioned RCBS presses as the best. Dillon's ok. I've owned a LOT of them. But I like the RCBS strip primers.

I've loaded about 128,000 rounds since 2000, most of in on these RCBS progressives. This is only the second serious problem I've experienced and this one I caught before I got into trouble. So two real screw ups in 128,000 rounds is only a 0.0016% error rate. Not a bad percentage if it weren't for the fact that you only have to have ONE serious problem ever to get killed.

I'd like to end this with a couple of points.

First, if you can use a powder height checking die.

Second, Unique bridges - I wouldn't have guessed that.

Third, I've had two serious problem. One on a progressive and one on a turret. I think that progressives are actually safer (at least if you are old and getting forgettful) but no reloader (machine or human) is foolproof.

[arkypete]

Chuckle
A number of years ago I read an article in Handloader, that 800-X is the best powder ever made for 45 Colt.
Syncronicities do happen, a guy I met at the range had two four pound canisters that he wanted to sell cheap. I think I paid $25.00 for both.
Ahhh the fates were in love with Jim.
Took it home, changed dies on the Dillon 300, this Dillon is for experimenting, the Square deals and 650 are for production.
I found out all about bridging. Some cases would get five grains and some would fifteen.
I never got back to working with the 800-X but I will.

I think what needs to be done is open up the drop tube to larger diameter, put a longer taper in funnel section, and put a mirror polish on the inside.
Jim

[redbear705]

I have been loading 38 specials with 4 gr titegroup for my IDPA shooting.

The Lee turret press has turned out thousands of perfect loads over the last year......but I have been shooting so much lately I got the bright idea to set up the loadmaster in 38spl and get the reloading done quicker.

Well as luck would have it I was at a match and had what I thought was a bad primer as I did not hear it go off. I did a quick reload and took the second shot on the target when the stage was over the S/O came over and said did you see this?

There was an extra hole in the target......he told me that when I shot two holes appeared,so the primer did go off and set the bullet inside the barrel and the next one pushed it out.

I and another experienced gun hand checked out the barrel for the dreaded bulge/ring in the barrel but could not find one. We conjectured that the Ruger Security six was one tough handgun and I took the accidental abuse with no problem.So I continued shooting with it but with some ammo loaded before the press change.

I got home and disassembled 150 rounds and over half were without powder.

I am using the Lee Pro measure with the pucks in them and I guess the cavity is too small and the titegroup can bridge. The only thing we can think of is that the turret press moves and shakes alot during the process and on the loadmaster the measure just goes up and down with very little shaking and this causes the bridging.

As stated in an earlier post someone said that there should be a vibrator on the measure....well I thought the same thing so I went to an adult online store and bought one of those vibrating bullets (eggs)( :) ) I now have it hanging just touching the puck and vibrating on low.........this works great although ya got to put up with that dang buzzing noise! :-D

No more bridging but now I got 400+ to disassemble cause I dont like it went it dont go boom.......as a matter of fact this has added alot more time to my score because I have to be so much more cautious......JR

As a side note I cast my boolits as large as I can then I size them to .359" and lube both grooves with white label 50/50 I think with the oversize boolit and the extra lube the boolit could not get too far into the rifling,but let the cyclinder rotate and since there was very little distance from lead to lead there must not have been enough velocity to cause a huge deformation in the first boolit and let them both pass without damage to the barrel.

By the way the boolits were about one inch apart and right on target about 20 yards away.

JR

[Blackwater]

I'm with 44 man on not trusting the progressives. I wish I could get over this, but it's just not budging, and mostly (not all, but mostly) due to prior experience with bridging. One instance that comes to mind is the .270 Win. and H-4831, which I've shot tons of.

And I'm in complete agreement also with what ArkyPete said, "I think what needs to be done is open up the drop tube to larger diameter, put a longer taper in funnel section, and put a mirror polish on the inside." I have collected a number of powder funnels through the years, and most have the hole for .22 cal. ctgs. I've ramed out and polished some to various other calibers, and this really helps. It doesn't ELIMINATE ALL of it, but it helps minimize it with most powders. I still have to watch the .270's and smaller when using long extruded grain powders, but .... it IS better. With a progressive, you can't do this, but I've also taken to pouring long grained extruded powders slowly and at an angle into the funnel, so that they sort of swirl around a bit, and thus, mostly align themselves vertically, or nearly so, which helps them stack in the case more uniformly. I watch the powder level in every case, and some still need some tamping, or if that doesn't work, I'll pour the charge back into the scale pan and give it a 2nd chance to stack up right in the case. The 2nd pour usually sets up right. If not, I rethrow the charge and try again. There's just no substitute for observing powder level in each and every charged case. If not uniform, I rethrow. This hasn't really affected accuracy a lot, but my SD's are probably at least a bit tighter, and it sure does make me feel a lot better. With extruded powders, I think uniform powder column height keeps the ignition more uniform, and that's never a bad thing.

Get yourself several powder drop tubes, and ream them out for your most favorite calibers. Use drills just a tad smaller than the bullet's measurement, and by that, I mean at least 1/32" smaller, to maybe 1/16" smaller. Sure will help with most calibers with the bridging, especially with a caliber as large as .357".

I'd REALLY rather forget to change the drop tube and get powder all over my bench ONCE, by forgetting to change the larger powder tubes when loading .223, than to get some warmish .38 loads (or whatever) with too much powder in them. Drop tubes are pretty cheap, and in progressives, if I had the faith to use them, I'd DANG sure have a number of them reamed out to help ensure against bridging. Since I found out I'm now mortal, and no longer 10 ft. tall, bulletproof and immortal, it helps me enjoy loading a lot more. ;^)

[NVcurmudgeon]

Chuckle
A number of years ago I read an article in Handloader, that 800-X is the best powder ever made for 45 Colt.
Syncronicities do happen, a guy I met at the range had two four pound canisters that he wanted to sell cheap. I think I paid $25.00 for both.
Ahhh the fates were in love with Jim.
Took it home, changed dies on the Dillon 300, this Dillon is for experimenting, the Square deals and 650 are for production.
I found out all about bridging. Some cases would get five grains and some would fifteen.
I never got back to working with the 800-X but I will.

I think what needs to be done is open up the drop tube to larger diameter, put a longer taper in funnel section, and put a mirror polish on the inside.
Jim

I see that you are an 800X victim also. Years ago I read Ken Waters' two-part Pet Loads article on the .45 ACP. Ken said that 800X was the cat's meow. I don't know about that, but luckily bought only one lb. 800 X would not meter safely, let alone uniformly in either my RCBS Uniflo with small cylinder, or a Hornady pistol measure. With the same adjustment, two consecutive throws would vary from under starting load to over maximum. I started out reloading with a $12 press and a scale loading .45 ACP, and didn't want to go back to that primitive BPM (before powder measure) time. I amused the kids with a flaming powder trail in the back yard.

[chevyiron420]

i reciently had some bridging problems with my rcbs measure with unique. i was weighing every charge so i didnt get any bad ammo. i took the thing apart and found just a few, tiny, super fine strands of spider web i have seen. after cleaning it out i have had no further problems, but my 55 lyman is more accurate with pistol charges.-phil[smilie=2:

[joeb33050]

In the course of writing the chapter on powders and measures, and testing the many measures, I ran into bridging and recorded what happened each time-how much powder came out during each throw. We also got reports on bridging and measures from other shooters. Mostly bridging was found and/or told about with the stick powders like 4759,4198,4831-but there were reports of bridging with Red Dot, in the Unique family .
Aside from the spider web, never thought of that, there was agreement that bridging was caused by too-small a hole in the drop tube, and we could stop bridging by drilling out the drop tube hole. This was repeatable.
We had no reports of bridging with Unique, but did find that no measure tested would meter Unique with repeatability.
I'm left with the notion that I MUST look in EVERY charged case before seating a bullet.
joe brennan

[jonk]

Say what you like about Lee; and I say their progressive presses have a lot of issues- but their powder through die is damned near ingenious. If they had a solid bar instead of the chain and a bit better dispenser but with the powder through arrangement it would be perfect for pistol and straight wall rifle.

[tomf52]

I have experienced powder bridging of Unique in my RCBS measure also.

[44man]

We just have to learn to not depend on anything. Leave nothing to chance!

[BOOM BOOM]

HI,
I am sure I have experenced Bridging w/ extruded powders.
This thread has covinced me that some of my lite & heavy load experances w/ unigue & 700X were powder bridging. I had not thought flake powders did that.
Have not used ball powders till this year , so have not had any prob. so far.

[KYCaster]

I'm left with the notion that I MUST look in EVERY charged case before seating a bullet.
joe brennan


I came to the same conclusion many years ago. I will not put a bullet in a case without first looking at the powder level in the case.

Jerry

[leftiye]

Not that this will end all variations, but I expect bridging would quit forthwith if you rap the handle against the stop at each end of the travel. I am aware of hangups in the powder flow having happened and have noticed that every charge doesn't fall the same. The only reason I think I'm aware of this is because of these hangups having come loose due to this bumping the handle top and bottom of each stroke. I bump it twice top and bottom.

If you aren't in control of the handle, then smack the powder measure with something after each drop, plus when the powder drops into the measuring chamber. With today's electronic scales, weighing each charge becomes a much less painful option, no more sitting around watching the beam play tiddlywinks.

[georgeld]

Hmm, very interesting.

I've had differing charges with a few powders and always just blamed
it on in accurate measures.

Good post, good advice and I always recommend to newbies one of the
most important tools in reloading is a flashlite to look down into every case.
before the bullet goes in.

I had a visitor afew yrs ago. Him and his buddy had questions about my
reloading practices. SO this a/hole and I started loading and I let him charge
the cases. The first 50 in the block had three without any powder in the case
when he handed me the block of charged cases.

I caught those with the flashlite. It sure p'd me off to see those and took
all work away from him and told him to just sit and watch, as I didn't trust him.

It wasn't until after he'd left that my wife found a letter he'd written to the buddy that he'd "checked out Georges' loading procedures and I'd caught all his deliberately skipped cases". OHHH man did I ever come unglued when I read that!! It's sure a good thing he'd already left, or I wouldn't be out of lock up yet.

I learned something over that: DO NOT trust ANYONE to help!!