powder measure ?

[crossdraw]

I have a RCBS Uniflow powder measure that I can't get to throw consistent loads no matter how careful and repetitive I try to be. Does anyone have ant tips on making this thing work.

I get loads that really vary from a few twists of the powder trickler to bring the weight on target to several twists. I have been measuring each load on the scale (using Unique).

Also, when I seat and crimp the bullet I sometimes get a small ring of lead just forward of the case rim (above the crimp) where some lead was scraped from the bullet as it was seated. Is this normal? When I do a final inspection of the bullet I use a scribe to clean the ring off.

I loaded 30 of these 200g FNRP with 8.0g of Unique as a starting point. They shot well, not real tight groups but that may be me and not the bullet. I am going to load a few at 8.5g and see how they shoot.

Thanks for the help.

[Machete]

First what is the differences in the measures, it may very well be alright if it is very small and if you are new to reloading it could be just getting constant with your physical throw of the lever on the powder measure.  On the shaving of the lead of your bullet, it sounds like you are not flaring the case enough, readjustt your flair die.

Machete   

[Driftwood Johnson]

Howdy

I used to use an RCBS Uniflow powder measure when I was loading on my single stage. Frankly, no powder measure is going to give you exactly the same charge every time, no matter who made it, or how careful you are. Your charges will all vary a slight amount. That's because powder measures portion out the powder by volume, not by weight. The powder flows down into a set volume in the rotor, and when you rotate the rotor you cut off the amount of powder in the cavity. The powder never fills up the cavity with the exact same amount of powder every time. Even with commercial ammo, they usually portion out the powder by volume, not by weight, and if you pulled some bullets off of commercial ammo I'll bet you would see some variation in powder charges too.

The other part of the equation is that not all powders flow the same, so some meter better than others. Generally speaking, flake powders like Unique do not flow as smoothly and evenly as a ball powder. Think about it for a minute. You are asking a bunch of little tiny flakes to flow evenly and fill up a cavity the exact same every time. They simply will not do that as consistantly as little balls will.

Let's get down to real numbers. With 45 Colt and 7.5 grains of Unique I would usually be able to keep my charges within +/-.1 grains with my RCBS measure. That means an actual spread of .2 grains. Although sometimes I would see a variation of as much as +/-.2 grains. That's why I NEVER venture near the max charges with a mechanical measure like the RCBS, or the Hornady measures on my progressive presses. I always prefer to stay a bit below max, so that even with some variation in powder charges I know I will be below the max charge. Bear in mind too that the larger the charge, the larger the variation will probably be. Variation will be proportional to the size of the charge. If I was throwing 30 grains of Unique I would expect to see a larger variation.

Don't forget, a trickler is capable of metering out powder one Granule at a time. It probably takes several turns of it to equal a couple of tenths of a grain. Frankly, I stopped using my trickler years ago. Like most beginning reloaders, I thought I needed one. I never use it any more. I simply am not trying to get powder charges exactly the same any more. If I was shooting long range precision rifle, it would be a different story, and I would probably be weighing each powder charge and using my fingers to trickle in every last tenth of a grain. I discovered long ago that I could trickle powder just as well with my fingers as with that silly trickler. But for mass produced CAS pistol ammo, I don't worry about trying to get my charges exactly the same.

The more consistantly you throw the handle on your RCBS measure, the more consistant your charges will be. Every time you throw the handle, if you allow the handle to 'whack' against the stop with the same force, you will be trasmitting vibration to the mechanism. Keeping that vibration consistant is one of the factors in getting the powder to pack as consistantly as possible in the cavity. Also, make sure it always has a good amount of powder in it, so gravity is always packing the powder into the cavity as consistantly as possible. If you let the powder in the hopper get low you may get more variation in your charges. I don't know, but you may be able to add a powder baffle to your RCBS measure. A baffle is a formed piece of sheet metal with a couple of holes poked into it. The idea is to lessen the effect of gravity on the powder charge, the total weight of the powder in the charge is not bearing down on the cavity in the rotor, just the weight of the powder under the baffle. Frankly, I've never felt the need to add a powder baffle to any of my powder measures.


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If you are shaving lead off your bullets you probably need to bell your brass a little bit more. Your brass should have a bell on it just big enough that bullets slide in without shaving off any lead, no bigger.

[crossdraw]

Ok, Thanks for the answers. I wasn't sure how  accurate I should be. It makes sense that CAS loads can be within in a range rather than an exact load.

I will try to bell the brass a little more.

[Delmonico]

I use a Redding BR3, it is considered the most accurate unless you go to a Sincliar or a Neil Jones made for bench rest at high $$$.

Very consitante, even more if I keep it set so the chamber is not full while I work, pull down on the lever, count to 5, pull up, will drop any powder in at under 0.1 grain each and every time, that method will work with any measure, working the press and other tasks on the bench while the chamber is full will cause problems.

[crossdraw]

Delmonico
Thanks, I will try your method. I reloaded some 38's yesterday for a friend and I got consistent measures each time. With the larger .45 load I don't, not sure why.

[Pappy Myles]

Ditto on what Driftwood said............Uniform throwing on a volumetric thrower is a function of technique and power granual size.

I use titegroup out of a little dandy, #8 rotor.   It spits out about 5.8 grains consistantly when I'm on the road and forced to single load.

On my progressive press, I do have a uniflow, but I changed out the plunger with one I had my gunsmith make for me. Its using the small hole drum available from RCBS, and works with their competition micro adjustment knob, also available from RCBS.  I removed the green plastic resivor and modified my thrower to accept the sinclair collar that allows me to screw on a 1 lb bottle directly.  The collar has a smaller diameter hole in it that the power flows through and it acts like a weight uniforming baffel.    Works out really nice.     Of note, I did present some pictures and drawings of it to RCBS at the NRA show in Houston, but unfortunately, it wasnt well recieved as under the NOT INVENTED HERE syndrome.     

My plunger is similar with the redding bench rest thrower in that the bottom surface is dished so there is no square corners on it.  It made it a lot more uniform on the case activated link, but still +- .1 grain.  However, the smallest load I can throw out of it is aboit 2 grains,   but who uses that small of a load on anything.........