Dillon 550 Powder Operating Rod

[DogmaDog]

Hey all,

I was reloading on my 550B last night, and found that my powder charge weight lessened by about 0.1gr over the course of about 100 rounds. Looking for a cause, I found that the little blue plastic wing nut on the bottom of the powder measure operating rod was turning loose by about 1/8 turn with each pull of the handle, and I think this was ultimately causing the powder bar to not fully return to its starting position.

The powder charge bar and the levers attached to it also seemed to move a bit jumpy. I've cleaned them with acetone, but no lubricant. Should I be doing something else, maintenance wise?

Questions:

Anyone else have this problem?

Have I diagnosed it correctly?

How did you solve it, or how would you recommend solving it?

Thanks much,

DogmaDog

[CSEMARTIN]

I have had this problem before. When this happened to me, I took everything apart and cleaned everything. I also took the powder assembly apart and cleaned the powder bar.

After reassembling everything, I always make sure to tighten the wing nut so that as I'm seating the primer the spring above the wing nut is almost entirely compressed. I have never had an issue since doing this.

[blue edge]

hey dog, try the hardware store for a nylon locknut, set it and forget it!

good luck blue edge

[EricW]

Have Dillon send you a new Tinnerman nut. It's the metal piece that's inside the blue piece. No lock nut is necessary. If the nut's still loose, the threads on your rod are worn out, and you need a new one of those.

Define "a bit jumpy."

Nothing in the powder mechanism should be binding when it's operated with no powder. Some powders cause a lot of sticking. (I went through hell with H110 a while back.) If the powder is the issue, try using double springs on the powder slide ($2 from Dillon).

If that still doesn't work, consider changing powders. If you're loading standard loads in 9/40/45, something like Titegroup works wonderfully in all and meters extremely well...and it's cheap.

Hope you get it worked out.

E

[ErikW]

The rod should only be a failsafe mechanism, to close the "open" powder bar. The case and funnel activate the powder bar. If the rod adjustment can change your powder charge, that's news to me. A tenth of a grain? C'mon! I haven't tried a powder that doesn't measure plus or minus a tenth from your set charge.

BTW, my wing nut is always loose too. And I have a 650 but I think the new linkage powder measure is the same for everything. (As opposed to the old spring-closed powder measure.)

[Nik Habicht]

My experience using an electronic scale is that my powder charge always varies + or - .10 of a grain. I try to load my 147s with 3.6 gr. of W231, but I generally get weights from 3.5-3.7 when I check individual cases. Throwing and weighing ten charges at a time I get the scale to consistently weigh 36.2 - 36.4 grains.... and that's close enough for me. If you think something might be busted, I'd certainly check it really regularly, but might it be possible that you just noticed something for the first time?

[ChuckS]

Mr Dog,

The powder measure works on a volume principle. Your turn the little nut in or out and the cavity in the bar opens or closes. I feel pretty confident that the nut does not eailsy turn by it's self. So, what else can happen? As you use up powder, the load on top of the powder that falls into the cavity decreases, compressing the powder less as the powder is consumed. It makes sense that charge might decrease when the powder measure approaches empty. I usually top off when the tube approaches 1/3 to 1/4 full. Seems to give pretty good results. I have found that if you leave the press sit (example: fill some primer tubes) the powder in the cavity will compress some, giving a charge of .1 to .2 (with N320, W231 is worse) gn heavy. I just manually dump about 5-10 loads into a paper cup and dump it back into the measure, then continue loading.

Now, what kind of scale are you using? If you are using a digital scale with a 0.1 gn resolution, you could be measuring anywhere from x.051 gn to x.149 gn as x.1 gn. You can see from that it is possible to be on a .001 gn threshold of a lower measurement. Check the manual for the scale and look for the accuracy. You may find something like +/- 0.1 gn accuracy. Electronic scales can have some drift over time and temperature. Perhaps re-calibrating and re-zeroing the scale would help. What I like to do is get an item that's about the same weight as the load you are using (something like a washer or button or something) to use as a check weight. Just leave in on the scale and when you are ready to check a load, you can see if there was any drift. Sorry for overanalyzing this but I am an electrical engineer by trade with a strong tendency to overcomplicate things!

If you are using a beam, then you have a pretty good idea what is going over time since a balance should be fairly stable over the amount of time it takes to load 100 rd.

[Sheldon]

Sounds like the powder in the measure is settling in. I take it you have the newer style powder measure where there are no springs on the powder measure? Is the weight continually decreasing or just after the first 100 rounds? I notice that if you don't stroke the handle the same everytime you will see some variation in the powder charges. Once you get going you get into a rythem and that's when you start to see better consistancy in the charges.

[DogmaDog]

Thanks for the help, guys.

I think my nut does have the little metal piece in it. I'll have to look.

Anyway, the .1 grain decrease is systematic. I also throw 10 charges and weigh them, and get some variation, but noticed a systematic decrease over the course of 100 rounds. It looked to me like the powder charge bar wasn't returning completely to the left after each pull of the handle, and I thought that might be because of decreasing tension on the failsafe rod.

I'm using a Dillon electronic scale (+/- 0.1gr).

Well, it's probably partly due to my recent 9 month absence...I've forgotten most of what little I knew about reloading. Wars are really inconvenient. I did save up lots of cash though.

DogmaDog

[Flexmoney]

Sounds like something could be loose or dirty.

Tear it down and build it up...it likely has missed you, and wants attention.

[DogmaDog]

OK,

I cleaned it up a little. And I set the nut so that the spring is about half compressed when the primer goes in, and I put some electrical tape on it to keep it from spinning. I threw three sets of ten charges, and got an extreme spread of only 0.3 grains, with no single charge more than 0.1gr away from what I want, so it looks like it worked OK.

I loaded a few rounds without any problems, until the primer bar started sticking, and failing to pick up a new primer every once in awhile. Guess I need to clean that too.

Does anyone lubricate any of those parts with a dry graphite lube or some such? I don't want to use oil anywhere it could contact primers or powder, but it seems like some of those sliding bars could benefit from easier sliding.

Thanks,

DogmaDog

[ChuckS]

May I call you Dogma?

I have tried it both ways on my old 550. I noticed that after ~500 rounds or so there is enough crap (decapped primer crud, brass flakes, powder, etc) to have some influence on the smooth operation of the primer bar. I take off the bar and clean the bottom side and also clean the shim it rides on. I will wipe it off and then polish both surfaces with 400 and 600 sandpaper. I got this machine used and it appears that there was some corrosion on the parts at one time and they are a bit pitted in spots. If your press is newer than mine (late 80's I think), cleaning should suffice.

I have left the parts dry and also have tried a lubricant. The last time I tried 10W30 synthetic motor oil. I have used Break Free also. I really did not get any signigicant improvement wet compared to dry. The only real difference to wet is that the crud mentioned above is in paste form! Probably the key to the thing working well is a good tip on the primer mag, the proper tweaking of the operating wire and the proper alingment of the primer cup in the shell plate. Also make sure that the two little pullys that the operating wire ride on are aligned to each other so no force is wasted trying to push either wheel to the side. Keep things clean and all should work well. If you do lube, just do it spairingly to the shim and stay away from the sides and top of the primer bar.

Later,

Chuck

[dillon]

On the 550 priming system, we suggest the following:

Use steel wool or a scotchbrite pad to scrub the top of the frame where the primer slide rides on it, scrub the sides and bottom of the primer slide,and the inside of the primer housing where it fits over the primer slide. Then wipe these surfaces off with an evaporating, petroleum based solvent. No lube on the primer slide, but grease the short end of the operating rod whre it inserts into the clamp on the primer feed housing.

[ErikW]

Let's look into this powder rod thing a little closer.

Is, or is not, the powder charge affected by the amount of spring compression at full stroke?

What is the proper adjustment for the spring and wingnut?

[calhunter]

Let's look into this powder rod thing a little closer.

Is, or is not, the powder charge affected by the amount of spring compression at full stroke?

What is the proper adjustment for the spring and wingnut?

<{POST_SNAPBACK}>

The Dillon Manual says that the spring should just touch the bottom of the washer when the handle is at rest. That should compress the spring about 50% when pushed fully to the rear. I don't think the amount of spring compression would affect the powder charge, unless there is a problem with the powder measure bar hanging or sticking. The spring is just to put a little pressure on the measure bar to make sure that returned to a full home position.

I put one of the springs from the old style measure on the new one. I had a problem with powder spilling on the upstroke of the handle when the case comes out of the die. The spring gives the measure a kind of annoying snap, but cured the spilling problem and seems to make the powder throws a little more consistent

Dogmadog - Mine did the same thing. If you take the Tinnerman nut out of the plastic wing nut and bend the two tabs in where the rod goes through it should stop the nut from backing off. I would use a pair of Vise Grips or Pliers, just tweak it enough make it tight on the rod.