RCBS Uniflow Powder Measure keeps doing me wrong

[jski]

I got some .45 Special brass from Starline for my .45 Colt S&W Mountain Gun. I decided on RamShot True Blue powder with my 255 gr., GC, hard cast bullets.

7 gr. of True Blue seemed like a good load.

Used my Gem Pro 250 to weigh the charges thrown by the RCBS measure. Got consistent 6.9-7.0 throws a consecutive throws and tightened the measure screw. I reloaded 100 rounds and re-measured.

I got 9.4 gr. INCREDIBLE!

I just ordered an RBCS bullet puller. Probably shouldn't use RCBS but they got the best reviews on MidwayUSA.

Any thoughts?

 

[WestKentucky]

RCBS is top notch on customer service and the uniflow gets good reviews. I have had 2 and sold them both to recoup the entire purchase price of the lot that they were in, but while I had them they did well enough. It’s very odd for it to go that far out. I would call a RCBS and talk to them. They may be able to sort the issue out if you give them the chance to.

 

[ColtPythonElite]

Odd....Mine is over 25 years old and still works great. I used it this week to load Unique. It was within a tenth of a grain in either direction.

 

[cp1969]

Because of slack in the threads, you should always tighten the nut before you check weights of charges.

But this would not account for a 30% difference. Maybe .1 or .2 grains, if that.

How many of the 9.4 grain loads did you get? One, or a string of them? If you got repeated 9.4 grain loads, either the adjustment on the measure changed or your scale is off. If you only got one, I'd say you had some powder bridging occur.

 

[jski]

Guys, I placed the reloaded cartridges in a 100 round case in sequential order.

So I decided to experiment: I weighed the first 4 and last 4 rounds with the Gem Pro and got 368.92, 368.92, 369.26, 368.38, ... 370.48, 369.98, 371.92, 371.02. Now I understand that there are variations in the weight of the bullets and cases but there does seem to be a trend here.

 

[jski]

I just repeated weighing the charges now thrown by the RCBS measure on the Gem Pro and I get a consistent: 9.48-9.5 gr.

I have NOT touched the powder measure adjustments since I set the thing before reloading.

 

[Dudedog]

Side note.
RCBS hammer type bullet puller has/used to have (still has?) a lifetime warranty.
Most of the other ones don't.

 

[WestKentucky]

Side note.
RCBS hammer type bullet puller has/used to have (still has?) a lifetime warranty.
Most of the other one don't.

Yeah and the cheapie baby blue one I have has broken the head off a half dozen times but superglue fixes it til it breaks somewhere else. Last time the blue one bounced off my forehead. I’m back to using the green one again.

Does anybody make one that uses shell holders? I might just put that together with pipe fittings. Will bend but not break... will have to pad it to eliminate risk of throwing sparks I guess.

 

[ColtPythonElite]

I have a blue one from Midway that I have had 20 years. Never broken it. I use Lee shell holders instead of the rubber band collets.

 

[jski]

I went with the RCBS Collet Bullet Puller.

 

[Arkansas Paul]

I hope you learned your lesson and won't load 100 freaking rounds again without checking your powder charge.
That's too big a risk.

I weigh every 10th powder charge. That way, I'll never have to pull more than 10 at a time.

 

[JimKirk]

This is a simple failure on the reloaders part .... Not checking the thrown charges on a regular intervals ... If the stem screw was locked right ... There is no way a proper functioning Uniflow would vary that much especially with True Blue powder ... that powder is very fine grain and will measure as well as any powder out there ... I have used a RCB S Uniflow since 1969(the same one) ... loaded 10 of thousands loads ... with a fine powder I have never had any such variations as the OP .... 800x is the worst powder I ever tried to meter ... even it meters closer than what is described above ...

I check every ten charges ...

I did change to the micrometer stem back about twenty years ago ... It makes no difference in the way it meters ... it just changes the ease of making adjustments ...

 

[Rule3]

A collet puller is not the "best" choice for LEAD bullets

You can not accurately determine powder charge in LOADED ammo

I doubt the powder measure"did you wrong"

I;ll stop now as others have covered the finer details.

 

[jski]

As long as we're on the subject, WHAT is a good choice for pulling cast bullets?

Why isn't it a good choice for pulling cast bullets?

 

[Navy_Chief]

The only time my Uniflow has shifted during loading is when I have failed to ensure that the stem was tight in the drum with some tension on the knurled lock nut.

 

[higgite]

Your thread topic says your Uniflow keeps doing you wrong. How many times has this happened?

 

[buck460XVR]

Large RCBS powder cavity or small? Do you use a powder baffle? As has been said, tightening the nut and then not verifying the powder charge again after tightening the screw can cause some variance. So will settling of the powder in the hopper after the thrower has been jiggled a few times or if more powder is added to the hopper.. Checking the charge weight every 20 rounds or so means one only has to pull twenty rounds and not 100. The Uniflo is a pretty simple design. Hard for it to change charge weights on it's own, biggest issue is when powder, due to static charge gets hung up or density of the powder is changed by settling. Did you look inside all the cases before seating a bullet to make sure the powder charge was the same in all of the cases? I would think a 25% increase from one case to another, would be easily visible, even with such a small charge,

 

[Ole Joe Clark]

From the git go looks like operator error. Do you have any reloading manuals, have you read and studied them? If you had, you would know that you don't load 100 rounds of anything without checking the powder charge.

 

[bearleft]

This may not be the case but...My New RCBS powder drop was very inconsistent dropping RL-22, took it completely apart the internals were coated with a thick rust preventative. I used Mineral spirits and wiped it down, and it's dropping good now. Also I completely wipe the entire unit with a dryer sheet before every loading session.

 

[Rule3]

I have a dual drum RCBS Uniflow. As with most all powder measures of this type it is a real simple design.

The rotor has a fixed size hole. The adjustment screw closes down the hole to different sizes. There is little to nothing that can go wrong.
Take it apart if it is clean(not rusty) and has a light coated of powder dust(graphite if you will) then it is fine. It's all in the tiny adjustment and locking of the screw Some powders as always meter better than others but not vary by 2-3 grains!
Mine doesn't have the high tech micrometer which to me is just a screw with lines on it.(which mine has)

Seems it is "something" else.

 

[jski]

I noticed this tendency to drift upward with my .30 Carbine reloads. But I was using ~15 gr. of H110 and in a .30 Carbine case that pretty much fills the case, so it was very noticeable. And I'd correct. So recently I disassembled the entire Uniflow, cleaning everything. I assume this would remedy the problem. Obviously I was wrong!

But even with the smaller .45 Special cases, overcharging AIN'T that noticeable, unlike the .30 Carbine.

Which leads me to ask: mechanically, why would the RCBS measure drift up?

 

[buck460XVR]

Which leads me to ask: mechanically, why would the RCBS measure drift up?

It doesn't.....mechanically. The powder settles, making it more dense and thus weighing more, while measuring the same volume wise. It drifts as the powder settles. Why most of us use powder baffles. I used a pattern readily available online to make mine outta some copper roof flashing. Again....are you using the small or large measuring cylinder? When loading with very small powder charges, I find the small assembly works much better than the one that usually comes standard with the thrower(large). It also does not "drift" quite as extremely as the large cylinder assembly with small powder charges. Many times folks will "throw" the powder back into the hopper as they try to "set" the thrower to throw the correct charge. This tends to compress the powder making it more dense. Again, checking the charge weight of thrown powder charges every so many cases is pretty m,uch standard procedure until one is fairly confident their charge is not going to change. If, like you, I have had problems in the past with other powders and other calibers with my thrown charges "drifting up", I'd be checking every ten cases or so. It takes much less time and effort than pulling bullets and makes for better and safer ammo.

 

[Navy_Chief]

It doesn't.....mechanically. The powder settles, making it more dense and thus weighing more, while measuring the same volume wise. It drifts as the powder settles. Why most of us use powder baffles. I used a pattern readily available online to make mine outta some copper roof flashing. Again....are you using the small or large measuring cylinder? When loading with very small powder charges, I find the small assembly works much better than the one that usually comes standard with the thrower(large). It also does not "drift" quite as extremely as the large cylinder assembly with small powder charges. Many times folks will "throw" the powder back into the hopper as they try to "set" the thrower to throw the correct charge. This tends to compress the powder making it more dense. Again, checking the charge weight of thrown powder charges every so many cases is pretty m,uch standard procedure until one is fairly confident their charge is not going to change. If, like you, I have had problems in the past with other powders and other calibers with my thrown charges "drifting up", I'd be checking every ten cases or so. It takes much less time and effort than pulling bullets and makes for better and safer ammo.

The baffles are definitely important to throwing consistent charges, so is ensuring that you move the actuating lever the same way every time with the same amount of force. My normal technique is to tap at the bottom of the stroke before rotating up to settle the powder in the measuring cavity and tap again at the top of the stroke to ensure that there is no powder stuck in the cavity. I think that this also ensures that the powder below the baffle in the hopper stays consistent. Hard to explain but I think that covers it.

 

[Rule3]

Baffles are not really that important.
The hole in the rotor fills up with or without baffles in the powder measure, Just the movement of the press and measure shake the powder around enough.

If no baffle used, just keep the powder measure 3/4 full and no worries.

 

[R. Cobb]

The baffles are definitely important to throwing consistent charges, so is ensuring that you move the actuating lever the same way every time with the same amount of force. My normal technique is to tap at the bottom of the stroke before rotating up to settle the powder in the measuring cavity and tap again at the top of the stroke to ensure that there is no powder stuck in the cavity. I think that this also ensures that the powder below the baffle in the hopper stays consistent. Hard to explain but I think that covers it.

I would like to add this.

While using the powder measure, and you feel a slight hang/change in the feel while dumping the charge into the case you are cutting a grain of powder in half which will make that charge +\- different.

When I feel that glitch in the handle I automatically dump that case back into my hopper.
I also run several powder throws before I do any scale measurements. Then about 5 throws before I’m satisfied I’m where I’d like to be.

Just my 2 cents.