Home Forums Reloading Big Game Rifles Problem with H4831sc and RCBS Uniflow

I was preparing some last-minute loads for deer season and ran into trouble-- thought you guys would have a suggestion or two.

I was loading H4831sc into 25-06 using a RCBS Uniflow powder measure. I was loading into the pan of my RCBS 5-0-5 and measuring each load, and topping off with a trickler as needed. The variation, round to round, coming out of the measure was downright dangerous. I'm talking 20 grains +/-! I figure the problem was the H4831sc was sticking in the measure. It made for a very long session.

Is there a simple way to fix it? I did a batch of 30-06 with H4895 right after, and had zero problems.

Throw with a rhythm; As you bottom out the handle, give it two taps (just don't crank the handle back for another charge)!

A charge that is cutting excessively and every time is going to have a large weight variance. Try to find a charging rhythm (usually a brisk handle operation) that reduces the cutting.

Doing things slow and deliberate usually makes for a lot of work.

H4831SC is a ton better for metering than the old H4831, but I've never even seen a 2 grain variance with that stuff and the OLD H4831!

Check how the measure is mounted too. It needs to have full travel with the handle.

Excellent description on how you use the uni-flo measure. I do the same thing with mine.

Shaman, I've had the same thing happen before.

Remove the powder reservoir and clean the inside of the powder measuring chamber with a clean, dry cloth. Made sure there is absolutely no oil inside the measuring chamber because that will cause powder to stick. Remove the drop tube and clean it, and as much of the inside of the drop chamber that you can. Wipe everything down with a anti-static dryer sheet, then reassemble.

This will typically help.

I have never had this kind of variance. I use Harrell's measures exclusively.

To have that kind of variance, you must have bridging. The powder is probably hanging up in the drop tube. Do you have the proper parts installed?

You need to get the next larger drop tube for the measure, simply call RCBS they will send you one.-Muddy

This.

Sometimes we can miss the obvious.

I would check this, especially if trying to charge a 25-06 case!

Buy a baffle for it, Uniflow's like them. Guess that's why they make them.
Never drop to a pan, it can actually promote bridging.
Drop to a spent case into a powder funnel, then dump into the scale. Trickle from there you must.

Hmmm. I've got a baffle in, and I'm meticulous with my rhythm. I'm also using the large drop tube.

So I guess I'm going to take the booger apart. Clean it for the first time in 14 years and wipe everything down with a dryer sheet.

I'll let y'all know the results. THanks!

Sniper is right, especially if you haven't cleaned it in 14 years.

With the Uni-Flow (or my Hornady too), when running the heavy stick powders, I grasp the handle firmly by the whole shank so that when the grains bind and don't shear right away, without allowing any jiggling to let them settle one way or another, I use the firm grasp I have to cut the grains off. While that doesn't make a smooth even stroke of the handle, it is still as seamless as I can accomplish and it seems to be quite consistent. The tap-tap at the bottom (and top) of the stroke - consistency is critical- seem to avoid bridging problems in the drop funnel portion of the measure. If I don't weight individual charges after measuring, I at least view and compare all charged cases before I begin bullet seating.

Buy a Redding..problem gone!