Leaky RCBS Uniflow

[Seth W]

I bought a Uniflow new when I stared reloading last winter. From day 1, it has leaked. I do not know from where. What I have done so far is put a white plastic tray under it when I'm throwing powder. That catches a fair amount. I'd say at least 5gn per 100 rounds. (loading 40 S&W right now). I know I'm not spilling it. Meaning, I'm not dropping full cases, or missing a case and dropping on the bench. I put 50 cases into a loading block, and drop each charge into the cases. Still, I end up with powder in the tray, and powder on the bench. The other thing I've done is replace the nozzle that comes with the uniflow with an aluminum one I made that fits completely into the case. Trying to be consistent with lever action, drop time, and tapping the nozzle after the drop doesn't help, either.

So, is a certain amount of powder escaping normal?

 

[Mike Casselton]

No.

We'll need a good quality video to see what's going on.

BTW, are you absolutely certain you don't have the small screw in the large drum?

 

[Mike Casselton]

Also, the case mouth contract on the insert should only be the case mouth.
If your case mouth is going completely into the little drop tube, then powder is escaping around the outside of the case mouth.

 

[Mike Casselton]

Correct on the left.

Incorrect on the right.

 

[Seth W]

No, I'm not using those plastic RCBS pieces. I made some from aluminum, where the entire end goes inside the case. Loading 40 S&W, 9mm, and 45 ACP only. Also, the only 2 powders I have are A#2, and HS6. I'll try to get some photos posted.

Mr Casselton; positive. I'm using one I made. I made it because it was leaking with the RCBS part, too.

 

[Mike Casselton]

If you're inserting that small stem into the bottom of the brass and then dropping, it's not helping your issue.
Powder can stick in the tube and fall out after you remove the brass.

It should be pretty easy to diagnose.

Set up a sheet of white paper underneath your powder measure.
Drop powder into your brass and leave it in contact with the drop tube.

Observe.

Any spilled powder?

Yes/no?

Yes.

Is it falling out of the drop tube?
Yes.
Change the drop tube.

No.
Then it's coming from a very worn measure through the drum. Very unlikely though.

No.
Then it's most likely your technique and you're spilling powder when you remove the brass from the drop tube.


Are you absolutely certain your adjustment stem is fully tightened?

Do you have the small stem in the large drum?

To make this easy on yourself, set your phone up to video your process and it'll show exactly where the leakage is occurring.

Is the powder reservoir not fully seated into the measure?

If the drop tube doesn't seat fully into the measure against the shoulder, powder can accumulate around the circumference and then fall out as you manipulate the handle.

If the drop tube inner diameter is too small, powder can bridge and then fall out after you remove your brass from the drop tube. This is usually apparent when loading with large size extruded powders and forgetting to insert the large drop tube. It will also happen with large flake types of pistol powders.


^^^^ Those are some of the things that can cause powder to spill.