RCBS Uniflow question

[Spector188]

Hey all, I am relatively new to reloading so I hope you can help. I am using an RCBS Uniflow powder measure that is just giving me fits! I cannot seem to get a consistent throw no matter what I do. I am not sure if it's the powder, my technique, or the measure itself. it is basically to the point where I have to measure every single throw. So this it what I have: the Uniflow, the baffle, the old meter screw not the micrometer. I am using Unique powder and reloading 9mm and .45 ACP on a single stage RCBS press. Any help would be greatly appreciated!

 

[SSGSAD]

How much variance on each load ?

 

[Spector188]

I am seeing a wild swing actually. My load data tells me 4.5gn of which sometimes I will get 2 or 3 in a row, but then it will throw a 3.8 and then a 5.3. max gn for this particular load is 5gn.

 

[SSGSAD]

Tha only thing I can say, is sometimes, they are hard to set. Just keep trying, it should set, to within a .1 or .2 gr.

 

[patience0830]

Do you have the pistol chamber rotor? I tried it with the larger chambered rotor and thats a real no go. I'm real fond of that micrometer measure. I always tap twice on the down stroke b4 filling the shell. Seems to help. Gotta do it the same every time.

 

[Spector188]

Will a .1 or .2 variance make much difference in my loaded cartridge? I ask because I am really not sure if my goal is to get each cartridge exactly the same or if these slight variances are "normal" to the reloading process.

 

[Spector188]

I do have both size rotors though I am only using the pistol one

 

[billybob44]

Each to his own..

I have two Uniflow's. One set up for pistol (small drum), and one set up for rifle (large drum). All of my pistol powder charges average between "Right On" to +/- .1gr. All my rifle charges average between "Right On" to +/- .2gr.

My set up is different than the way most Reloaders set up their drum/handle. My (Non-Mic) adjuster is on the back side of my measure. Handle, in the front, set so when I raise it, it picks up the powder from the reservoir. When the handle is lowered it drops the powder into the case.

My "Learned Habit" is-Up-tap-tap==Down-tap-tap..Up-tap-tap==Down-tap-tap. Just a light tap-tap on the up+down stroke. This makes for a very accurate drop for me.
When I throw 4-8gr. pistol powder charges, it is usually RIGHT ON the scale weight!!

The only difference is the "Feel" with extruded rifle powder where you are actually cutting grains on the down stroke.

Most people pick up the charge on the down stroke, and drop into the case on the up stroke??? This just does NOT work for me. As I said-Each to his own...Bill

 

[billybob44]

Average them out..

Will a .1 or .2 variance make much difference in my loaded cartridge? I ask because I am really not sure if my goal is to get each cartridge exactly the same or if these slight variances are "normal" to the reloading process.

.1gr. +/- is considered normal variation.

Adjust the screw to where it throws the correct charge+lock down lock nut.

Throw TEN charges, and weigh each one of them, divide by TEN..That is your average charge weight. You will NOT notice on paper OR recoil .1gr. difference on a pistol load--or MOST rifle loads, for that matter...Bill.

 

[Spector188]

Thanks for the help and all the good info!

 

[Broom_jm]

Also, if your Uniflow is brand new, you may notice that it will throw more consistent charges, after you've run a few hoppers of powder through it. This builds up a very thin layer of carbon from the powder that "lubricates" the whole works. Set your adjuster to drop ~20 grains and run through a hopper or two...you'll probably be happier with the results, after you do.

 

[Leo]

Your powder choice is also part of the problem. Large flake powder like Unique is a lot harder to accurately meter than a ball powder like Win 231 or something. Those big flakes never settle the same twice. I have both cylinders for the RCBS uniflow and neither works great with flake powder. The Hornady works better if you have the small diameter pistol insert if you really like flake powders. I also use the "tap" method as metioned above. I can "feel" the difference when I throw the lever. If it feels like it hesitated or slipped through too easy, I just poor the case back out an hit it again. That seems to help when I weigh a few extra samples. Good Luck

 

[Leo]

If you ever want to experiment on how precise you need, find some factory ammo that you like how it shoots. Take 10 apart and weigh the powder charge. I have found as much as +/- .4 on Remington factory rifle ammo. That is almost a whole grain between highest and lowest. And the stuff really shot pretty well.

 

[Broom_jm]

I know this is a slippery slope, and maybe WAY more than the OP was hoping to get from this thread, but here goes:

Metallic cartridges are loaded by volume, with a measured weight confirming the volume of powder that goes into each case. If you take two cases and load them with the same volume of powder, but the weight of those volumes varies by a tenth or two, either way, the internal ballistics of both will still be remarkably similar. Because, again, metallic cartridges are loaded by volume.

Volumetric powder dispensers, like the Uniflow, do a pretty good job of throwing powder charges that have a very similar weight. They do an EXCELLENT job of throwing powder charges of a similar volume; how could they not? The vast majority, and we're talking probably four 9's, of manufactured ammunition is loaded STRICTLY by volume, with the loads not being individually weighed. Think about that.

If you want your volumetric powder measure to throw charges that WEIGH the same, or very close to the same, every time, Unique is not the best powder to choose. If you understand that the weight of the powder is the tail wagging the dog, and that volume of powder dispensed is equally, if not MORE, important, then Unique is still perfectly suitable for volumetric dispensing. Especially with the ol' "tap-tap" method!

 

[hammer24]

I double tap on the up and downstrokes as well. Keeping the hopper near full seems to help as well. I get very consistent results with unique and this method.

 

[lon]

I know this is a slippery slope, and maybe WAY more than the OP was hoping to get from this thread, but here goes:

Metallic cartridges are loaded by volume, with a measured weight confirming the volume of powder that goes into each case. If you take two cases and load them with the same volume of powder, but the weight of those volumes varies by a tenth or two, either way, the internal ballistics of both will still be remarkably similar. Because, again, metallic cartridges are loaded by volume.

Volumetric powder dispensers, like the Uniflow, do a pretty good job of throwing powder charges that have a very similar weight. They do an EXCELLENT job of throwing powder charges of a similar volume; how could they not? The vast majority, and we're talking probably four 9's, of manufactured ammunition is loaded STRICTLY by volume, with the loads not being individually weighed. Think about that.

If you want your volumetric powder measure to throw charges that WEIGH the same, or very close to the same, every time, Unique is not the best powder to choose. If you understand that the weight of the powder is the tail wagging the dog, and that volume of powder dispensed is equally, if not MORE, important, then Unique is still perfectly suitable for volumetric dispensing. Especially with the ol' "tap-tap" method!

Listen to this guy. Most Benchresters load a volume, not a weight.

I might be wrong...but I don't believe anyone but a World Class Bullseye shooter could tell a difference of .1gr, and probably .2 gr, in their load at 25yds with open sights.

 

[walker]

I do have both size rotors though I am only using the pistol one

Do you have the Quick Change Powder Measure. This is info from mime..... To prepare the Quick Change Powder Measure for use, the measuring cylinder, measuring screws, drain attachment, inside of main casting and powder funnel portion of main casting must be cleaned to remove the factory applied rust preventative. Failure to do so will cause inconsistent powder charges. __ Before attempting to throw a series of powder charges, set the powder measure for the maximum charge and run about a pound of powder through it. This will deposit a film on the inside of the measure and help the powder flow through more evenly and consistently. __ You may also check that the Metering Screw Assembly is in place. __ Align the Lock Pin hole on the side of the Metering Screw Assembly and insert into the Metering Cylinder, release the Lock Knob. Try to rotate the Metering Screw Assembly to insure that the Lock Pin is in place. Tighten the Knurled Locking Pin Retainer.

 

[Spector188]

All good advice, I was unaware of the volume insight. Thanks for clearing this up! I think I will try some 231 as well.

 

[Fullmag]

Unique is a versatile powder and it's in the load data for 45acp but it don't perform very well for that caliber. W231 is an excellent powder 45acp and Titegroup or HS-6 is a great powder for the 9mm.

 

[KevMc]

Unique is a little tough to meter, unless you do the tap.tap thing, due to the flake shape. I still use it because it performs well for me even with the varience.