Pistol metering cavity diameter of drum style powder measures

[cfullgraf]

Do you think the diameter of the smaller pistol/handgun metering cavity in a drum style powder measure makes a difference in how consistent the powder measure operates.

It is a given that the large cavity drums designed for rifle do not do well, for the most part, with handgun size powder charges.

I have four different drum style powder measures, an RCBS Uniflow, Redding 10-X, Hornady L-N-L and a Midway Indispensable. (The Midway indispensable powder measure was discontinued in the 90s. I bought it on close out because it came with two micrometer adjusters on the metering drums.)

The diameter of the pistol cavity, or small cavity drums that I have for each measure is:

Uniflow 0.4975" diameter

10-X 0.374" diameter

L-N-L 0.311" diameter

Indispensable 0.308" diameter

i stopped using the Uniflow for small handgun powder charges a decade or so ago when i bought the Redding 10-X. Ditto for the Indispensable. I do not specifically remember, but I would guess the handgun powder charges were not very consistent. I use the RCBS with the small metering cavity for small rifle charges like 223 Remington. The Indispensable had the rifle cavity installed for large rifle cartridges like 30-06.

The Redding meters very well, including flake powder like Unique and 700-X. In fact, I have modified a second 10-X for use on the progressive.

On the progressive, the L-N-L will throw a light charge once in a while that is not picked up by the powder cop die but leads to a noticeably lighter discharge in the gun.

I wonder if the smaller diameter cavities cause inconsistencies with flake powders. Do you think there is an optimum diameter?

Any thoughts or observations on this?

Thanks.

 

[fguffey]

Around here there is no shortage of powder measures, before the Internet the Uniflow came with both drums, a very precision reloader has used the big drum for pistol and rifle, I gave him the small drum, he has never mentioned an advantage one way or the other. I have 3 press that use the Uniflow, I have an ‘adapter kit’ that allows the use of the Uniflow for my 550B. I have the Little Dandy with 24 rotors, quite an investment, I have dial-O-Matics, Lyman black and orange, I have 2 Ohaus powder measures, I have Lee dippers, yellow, red and black. I have adjustable dippers, and I have the RCBS electronic powder measures with scales. There is no shortage of scales, two reloaders came over with a problem, I had enough equipment out for three people, the first question: I thought you had a RCBS 10/10? Nothing to do but get the 10/10 scale out.

F. Guffey

 

[GLOOB]

It should theoretically make a difference. It does for my dippers. I use 380 cases for most of my Unique dippers, but for the denser powders I tend to use 1/4 brass tubing.

 

[PO2Hammer]

From what I've been reading Unique seems to work better in larger drums, and those with the larger drums complain about Universal not metering well. My experience with my 10X is just the opposite, Universal meters flawlessly for me, always within +/- .1 grain, and Unique is rarely better than +/- .2 grain regardless of whether I double tap, leave the handle up between charges or move the baffle around.

 

[Walkalong]

I have thrown a lot of small rifle charges with my Redding 10X and my Redding BR-30. The 10X has a small "pistol" insert while the BR-30 has a "medium" size insert. There is not a stand up and notice difference throwing small charges (5 to 10 Grs) of pistol powders with them. There is a difference though.

Conversely, when throwing small rifle charges (20 to 30 Grs) of rifle powders, the BR-30 does a little better. Again, not a stand up and take notice difference, but a difference. The 10X can physically do .223 with some powders, but the BR-30 is a better choice.

In both cases, it is extremely close with some powders, not so much with others.

Since I bought an LNL micrometer rifle insert and started using the LNL measure for .458 Win Mag, I played with it and pistol powders, and gave up very soon. I cannot even imagine using the bigger rifle sized inserts to throw 5 to 10 Grs of pistol powders.

 

[rfwobbly]

Do you think the diameter of the smaller pistol/handgun metering cavity in a drum style powder measure makes a difference in how consistent the powder measure operates.

Great question.

No, I don't believe it does.

A smaller bore has to move the piston further to get the same amount of change as a large bore, but that simply improves the preciseness of the adjustment. As the cartridge gets smaller, measuring to fractions of a grain becomes more of a requirement. But let's not confuse adjustment ease or precision with 'consistency'.

I believe consistency has to do with several other factors.

• Coarseness and particle shape of the powder, which affects how it moves (tumbles) thru the hopper, baffle and rotor. Generally speaking, it helps to think of powder as a liquid in that it "flows", but this can misleading in that we forget granular coarseness leads to variations in internal friction which in turn affects the powder's ability to fill the rotor.

• Columnar pressure being generated by the height of the powder in the hopper. One pit fall in making an assessment would be comparing a Uniflow to a modern design powder measure that incorporates a baffle. To get an "apples-to-apples" comparison, one would have to fit all the contestants with similar baffles, similar diameter hoppers, and then fill the hoppers to similar heights.

• Vibration to settle the powder to a consistent density. Since we really are after powder weight, but we are dispensing volume, we must have consistent powder density to do this. Consistent density is only reached by having a steady vibration acting on the powder measure over time. So again, to get a true apples-to-apples comparison, you'd need to equally apply a consistent external vibration source to all the powder measures. (In the old days small fish tank air pumps were used for this job.) In a hand operated powder measure, absent of an independent vibration source, vibration is supplied purely by the operator's handle technique, which you must admit would be purely arbitrary. At that point, small details like the Uniflow's rotating knob versus the Redding's fixed knob may become important factors.

Hope this helps!

 

[Walkalong]

A smaller bore has to move the piston further to get the same amount of change as a large bore,

This definitely affects things. The ratio is important. I am sure that is why the 10X would not do as well with small rifle charges as the BR-30 would.

 

[rfwobbly]

But ah, my friend. Are we still discussing consistency in delivered powder weight, or have we slipped into ease of adjustment or a discussion of finesse of the adjustment mechanism ?

Would you still give the same answer for a large bore rotor, which had a piston with 500 threads per inch (tpi) stem versus a small bore rotor, which had a piston with only 10 tpi ??

 

[Jim Watson]

I don't have a wide selection of powder measures but a couple of anecdotes might help.

I was loading pistol ammo yesterday with the RCBS Uniflo Small + Micrometer. At every check weigh it was delivering either 4.3 or 4.4 grains of Bullseye.

My old Redding No 3 Master is now set up for black powder but early on (1970s) I tried it with the small insert and pistol powders in 3-5 grain charges. That was a nuisance. The insert did not fit perfectly flush with the drum and was prone to smearing granules of powder and binding the rotation. I like being able to select a powder cavity diameter to suit the load but I want complete drums for the job. Or these days, complete measures or a scale + dispenser setup.
Do other brands' drum inserts fit better? Hornady promotes theirs strongly.

(In the old days small fish tank air pumps were used for this job.)

Then around here "the old days" is last week.

 

[Walkalong]

Are we still discussing consistency in delivered powder weight,

Yes.

or have we slipped into ease of adjustment or a discussion of finesse of the adjustment mechanism ?

No

Would you still give the same answer for a large bore rotor, which had a piston with 500 threads per inch (tpi) stem versus a small bore rotor, which had a piston with only 10 tpi ??

Hmmm......but fortunately, they are all finely adjustable.

 

[cfullgraf]

Great information, thanks.

I agree with everything and the comments show there are lots of grey areas when it comes to operating a powder measure and getting consistency of charges thrown.

While I may not have been clear with my original post, i am looking to improve operation with flake powders. Or maybe learn a little more of the dynamics going on inside the powder measure.

From my experience and from the comments, I plan to modify a drum and metering insert for the Hornady L-N-L powder measure to a bit larger in diameter than the Redding 10-X, probably around 0.4 inches in diameter. Larger than the Redding but smaller than the RCBS Uniflow.

Why the Hornady, i have an extra pistol metering drum that I bought when ordering the Hornady progressive press. The published information at the time indicated the press only came with the large cavity drum. Also, the metering inserts are relatively inexpensive and easy to disassemble for machining. I will look at the micrometer adjuster though and see if it an easy candidate for machining.

I will post my findings but it will not be for a while as I have too many irons in the fire at this time. Also, I need to get some additional tooling for my lathe to be able set the drum up properly for boring.

Thanks again.

 

[rfwobbly]

Mr Graf -

Personally, I'd do the following....
• Polish the metallic funnel section inside the PM, just below the hopper cylinder. That might reduce sticking to the sides as the powder tries to tumble into the rotor.
• Make sure you have a good baffle in there. I've not inspected a Hornady measure well enough to form an opinion, I'll leave that assessment to you. If help is wanting, then drink a beer and cut up the can per This Article.
• Most any progressive press shakes enough to supply the needed vibration you seek. If you've done any "upgrades" to keep the PM form rattling and shaking, then I'd consider undoing those in the name of progress. Or, maybe hunt up a tiny fish tank air pump. Failing that, you can always set your cell phone to 'vibrate', duct tape it to the PM, and call yourself on each down-stroke.

All the best.

 

[Walkalong]

Most any progressive press shakes enough to supply the needed vibration you seek

I am not sizing while loading on mine, so the force on the ram is minimal. I lightly bump the handle at the bottom of each stroke, similar to bumping a measure handle when operating them manually. Works for me, and may partly explain why I have good luck with flake powders.

 

[cfullgraf]

Thanks, see comments below.

Mr Graf -

Personally, I'd do the following....
• Polish the metallic funnel section inside the PM, just below the hopper cylinder. That might reduce sticking to the sides as the powder tries to tumble into the rotor.

I have done that on the Hornady L-N-L powder measure. It is "purdy", not mirror like, but smooth as a baby's bottom. I really did not see any improvement. Also tried waxing the inside of the powder measure with Johnson Floor Wax. It made the measure slicker and powder sticks less to the inside surfaces, but again, I have not seen any improvement. But, i have just started experimenting with the wax.

• Make sure you have a good baffle in there. I've not inspected a Hornady measure well enough to form an opinion, I'll leave that assessment to you. If help is wanting, then drink a beer and cut up the can per This Article.

I have been a big proponent of baffles since the mid nineties. All of my drum style measures have baffles in them. In fact, i have been experimenting with two baffles in the Hornady measure, the upper one turned 90 degrees to the lower one and an inch or so above.

Also, I get better results when I insure the holes in the bafle do not line up with the metering cavity. The line of the leak of the baffle is installed 90 degrees to the rotational axis of the drum.

• Most any progressive press shakes enough to supply the needed vibration you seek. If you've done any "upgrades" to keep the PM form rattling and shaking, then I'd consider undoing those in the name of progress. Or, maybe hunt up a tiny fish tank air pump. Failing that, you can always set your cell phone to 'vibrate', duct tape it to the PM, and call yourself on each down-stroke.

When loading on the single stage press and batch charging of cases, I find better consistency if I minimize the vibration of the powder measure. i used to wrap the measure on the top or bottom of the stoke but not any more. Among other things, i find the charge weight thrown creeps up a tenth or two over a loading session, most probably due to the powder column settling. I get less of this creep when I do not vibrate the measure more than necesary.

I am not saying extra vibration, wrapping or other disturbances do not help other folks, I have found an alternate method that works for me. But as far as my quest is concerned, how the measure is operated is irrelevant as long as the powder measure is operated the same every charge thrown.

Towards that end, like Walkalong, i do not resize on the progressive when loading, but the measure get a pretty good knock on the down stroke of the shell plate.

All the best.

Thanks again for your suggestions.

 

[918v]

From my experience and from the comments, I plan to modify a drum and metering insert for the Hornady L-N-L powder measure to a bit larger in diameter than the Redding 10-X, probably around 0.4 inches in diameter. Larger than the Redding but smaller than the RCBS Uniflow.

All that work to realize that precision in powder metering does not translate to better groups on paper.

I have a 10x, Little Dandy, RCBS Competition measure and a Chargemaster. I feel the 10x is the best most precise pistol measure followed by the Little Dandy but only because it isn't adjustable. They are all +/- .1 grain accurate which is accurate enough to produce superb accuracy in capable firearms.

What I'm getting at is powder metering accuracy, if within .2 grains, does not affect the accuracy of the load.

 

[cfullgraf]

What I'm getting at is powder metering accuracy, if within .2 grains, does not affect the accuracy of the load.

I agree.

I am looking to eliminate the rare, occaissional light charge of flake powder that is off farther than that.

 

[918v]

It won't eliminate what you are looking to eliminate.

 

[Canuck-IL]

Another anecdote ... I had bridging issues with Clays using the Hornady pistol meter aiming for about 3.8gr ... 5-10 right on, then an almost complete bridge, then one slightly heavy, then repeat the loop.

I had put about 8#s of Bullseye through before starting on the Clays and BE really is dirty - before it's fired! Upon disassembling the powder drop to clean it I was amazed at the coat of sludge the BE had deposited. That layer was providing enough friction for the flakes to hang on now and then. Cleaned it all up, polished a little and things improved but, there'd still be one in 15-20 that bridged.

I ended up using the rifle meter for Clays and after a little fussing to find the right setting (see RFWobbly point above about ease of adjustment) it proved much more consistent for the flake powder.
/Bryan