SR4759 and bridging in power measure

[Wayne Smith]

I have a Pacific power measure and an RCBS.

I have recently begun using SR4759 and I know a bunch of you guys use it. In both of my powder measures I have had a major problem with this powder bridging. I mean so serious that sometimes nothing comes out. I have used 4831 and 4064 without as much problem.

I am surprised that a power this short causes such a problem. Am I the only one with this issue or is it common?

[looseprojectile]

Wayne, I use my Pacific powder measure for all powders. No problem with SR4759.
I have developed a system whereby I thack the handle at the top several times and at the bottom several times also. With ball powder it is not necessary but I give a couple of whacks anyway.
Some old powder measures have a weight installed that are made to flick and cause some vibration to get the powder to flow consistently. I took that as a hint to do what I do with the Pacific. I find that it helps to wipe the inside of the metal parts with the waxy clothes drier sheets to help eliminate static cling.
Man gotta do what he gotta do.

Life is good

[Wayne Smith]

I find it hard to whack my Pacific but easy on the RCBS. That said, even with the RCBS, when it gets down low it just doesn't want to come out.

[Thumbcocker]

It works ok in the measure on my dillon 550

[joeb33050]

Powder "Bridging"
Sometimes, with some powders, all the powder doesn't come out of the measure when the measure is operated. The next charge or the next can then be much larger than the planned or "set" charge. The powder gets hung up in the measure and doesn't come out on the first try, but comes out along with the proper charge later.
While charging cases with SR4759 using a Lyman 55 powder measure on 10/16/04, I had two instances of the powder not all coming out of the measure after flicking the knocker. This is two out of eighty-eight cases charged. I didn't measure the first instance. Note that this has happened many times in the past, 10/16/04 was the first time I ever measured what happened.
In the second instance, the measure dropped 5.6 grains of powder into the scale pan after flicking the knocker
After operating the handle and flicking the knocker again, the measure dropped 21.7 grains of powder into the scale pan. The powder that didn't come out before came out then. The desired charge was 14 grains of SR4759.
On 11/29/05 while testing a Lyman 55 powder measure there were two hang-ups. The charge was 18 grains of SR 4759.
One hang-up was charges of 4.3 grains, .4 grains, 0 = zero grains and 68.2 grains.
The other hang-up was 7.8 grains, 0 = zero grains and 41.9 grains.
While testing a powder measure designed and made by Mike Barrett, I had SR4759 hang-ups several times, to the point where I stopped testing the measure with SR4759.
In February 2006, while testing a Lee Perfect powder measure and old 20 mm cannon powder-sorta kinda 4831, John Alexander had a hang-up or bridging problem.
R. Dale McGee reported having powder hang-ups with 700X powder.
There have been reports of Red Dot powder hang-ups.
These experiences and reports suggest that some of the high-pressure incidents reported may be caused by powder bridging in the measure, with the next charge being excessive.
You MUST look in each charged case with a flashlight!
joe b.

[GOPHER SLAYER]

Wayne, SR4759 is one of my favorite powders and I have experienced what you described many times. That is why I weigh every charge. I have had the same problem with other stick powders. I have at least ten measures, so that is not the problem . If I ever get around to using my Lee progressive press for pistol ammo I will only use a ball powder.

[Rocky Raab]

That's why I use an electronic dispenser/scale combo almost exclusively. Those big inch-high numbers are a hint when something isn't right.

On the rare occasions when I want to use a powder dispenser, I get out my JDS QuikMeasure.

[Blackwater]

Those little plastic nozzles the powder flows through are cheap. I used to use only the .22 caliber nozzle until I discovered that the .30 caliber nozzle just about eliminated powder bridging. Of course, you can't use the .30 caliber nozzle with anything smaller than .30, and I loaded a .270 a lot, so I got another .22 cal. nozzle and drilled it out with a 1/4" drill, and that lessened the bridging by a good margin.

Easiest and best solution to your problem with bridging is to get several, like maybe 3 or so, new .22 nozzles, and drill them out for the calibers you shoot. That will reduce your powder bridging as much as you're destined to be able to for a given caliber. Cheap, too.

[Calamity Jake]

ON the RCBS I take the plastic funnel out and don't use it when using 4759 to stop the bridging.
I use one of the hand held case charging funnels under the measure. I alse do the double tap on both the charge stroke of the measure and the dump stroke.

[Pepe Ray]

AWTTW;

POWDER BAFFLE
Pepe Ray

[Boz330]

I do the double tap with the operating handle with all powders, but 4759 is a very light and fluffy powder so it is a little more prone to the bridging problem.

Bob

[Wayne Smith]

I have an old (+20 yrs) RCBS measure that has a metal, not plastic, nozzle. Perhaps that's why it has less a problem bridging, but it does. Yup, I guess I will just have to weigh those charges. I do for 4831, 3031, and 4064, so why not?

[fourarmed]

I double-tap my Redding top and bottom, but I also fill my cartridge block with cases, then fill them in order - up one row, down the next. When I inspect them, I inspect them in the same order in which I filled them. That way, bridging is easy to spot: an underfilled case is right next to an overfull case.

[1Shirt]

With any load that is not over half a case full, I check with flashlight, and after loading, I weigh each loaded ctg. It is important to have the same headstamp case and to seperate them by weight and keep them that way. Different runs of brass from even the same mfg can have appreciable weight difference. One double charge in my lifetime was one to many!
1Shirt!:coffee:

[watkibe]

My CH measure has 2 measuring cylinders and nozzles, one each for pistol and rifle. I always use SR4759 with cast bullet loads, I just put in the rifle cylinder and nozzle and make sure I operate the handle in a positive manner. At the end of the dispensing stroke, I jiggle the handle a little to make sure all the powder came out. One of the advantages of SR 4759 is that the loads are over half the case capacity, so double charging is obvious, and a one-and-a-half charge as mentioned above is easily noticeable. I don't have a problem with powder bridging.

What this makes me think of in general terms is how much of reloading is technique dependent. We develop our own style that meets our particular needs while loading safe and reliable loads.

[trk]

I took a carbide burr and smoothed out the drop tube (inside) on my Lyman 55's.

Agree with checking EACH case. Agree also with shaking the powder measure with the little hammer-weight at every opportunity.

[Dale53]

I was competing in a Bench Schuetzen match at the ASSRA Nationals at Etna Green, IN match with my CPA 44½ 32/40. My powder of choice was 4759 (I have a caddy of it). I was breech seating and loading at the bench. I experienced serious bridging as indicated here. My measure was a Redding with a .30 caliber clear plastic drop tube (the issue one). I discussed it with some of the old timers present. Several of them told me the solution was to get a rat tail file and make the drop tube hole, OVAL. I made it as OVAL as I could without exceeding the mouth of the 32/40 case. It TOTALLY solved the problem.

As with just about any aspect of reloading your best defense is to REMAIN ALERT. I picked up on this because I was PAYING ATTENTION. It was actually pretty simple as I was charging the cases individually and it was easy to see if the powder level in the cases was constant - or not...

OVAL worked for me, completely.

Later I changed calibers to the .32/,357 Dell and went to WC 820, a ball powder (similar in burning range to H110).

Dale53

[JSH]

Belding&Mull fixed my issue.
jeff