Hornady LNL Pistol Micrometer metering insert.

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Found one in my reloading tool chest I forgot I had. There was a pistol rotor assembly in there too.

I was wondering if there was a way to get a ballpark setting for a particular powder load.
First thing I noticed was the dial was not zeroed.
Fully inserting the micrometer stem locked it to the rotor against the powder measure housing. I backed off the stem until it could move, loosened the lock screw of the numbered thimble and set it to the zero line on the stem. Very few flakes of titegroup powder managed to get into the rotor and did not register on my electronic scale and balance scale.

Then I removed it from the pistol rotor and measured the diameter of the piston, 7.92mm = 0.792cm.
Next was to measure the stem
Measuring stem at at line numbers 1, 2, 3, 4 gave a stem length difference of 2.56mm± = 0.256cm per number.
There is another line in between the line numbers which is 0.5 value, which is equal to a full rotation of the thimble.

So Cylinder Volume per full number =∏ x Radius Squared x Height. in cm
0.12612cc = 3.142 x (0.396 x 0.396) x 0.256

 

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My Electronic scale just wouldn't settle down.
Had to resort to balance scale.

Good news.
Hornady's Pistol Micrometer Metering Insert is very consistent on powder throws, surprisingly so.
Talking .1gr accuracy with titegroup on RCBS balance scale up to highest weight I measured at 7.3grs (.32S&W Long case)

As for using the micrometer for accurate powder weights, yes to a point.

Using Lee's VMD #( Volume Mass Density) for Titegroup of .08475 and the CC volume number I derived from measuring the Hornady Micrometer of 0.12612cc per whole number on the stem, it was very accurate to what it should have been up to #3.0 on the stem.

It should have been 4.46grs by calculation and it came out 4.3grs on three consecutive throws. Still not too shabby.

At #0.2 on the stem it should have been 0.297gr. and I got 0.3gr.
At #0.3 on the stem it should have been 0.446gr and I got 0.45gr.
At #0.6 on the stem it should have been 0.893gr and I got 0.9gr.
At #0.7 on the stem it should have been 1.04grs and I got 1.0grs.
At #0.8 on the stem it should have been 1.19gr. and I got 1.5grs.
At #1.4 on the stem it should have been 2.08grs and I got 2.1grs.
At #2.0 on the stem it should have been 2.97grs and I got 3.0grs.
At #2.7 on the stem it should have been 4.02grs and I got 4.0grs.
At #2.8 on the stem it should have been 4.17grs and I got 4.1grs.
At #3.0 on the stem it should have been 4.46grs and I got 4.3grs.
At #4.0 on the stem it should have been 5.95grs and I got 5.4grs.
At #5.0 on the stem it should have been 7.44grs and I got 6.7grs.
At #6.0 on the stem it should have been 8.93grs and I got 7.3grs


Actual VMD's may vary as much as 15% from published numbers with different lot number and my Volume number for the stem of 0.12612 maybe be off also. My Titegroup lot was 1072307(1lb July 23, 2007) next line 160 actual lot #

Expected calculated weight was done by ( Micrometer stem # multiplied by 0.12612, my cc volume per full number on stem ) divided by Lee's VMD # for Titegroup .08475 to get expected charge in grs.
Error does grow with volume.

Still very useful. No powder drops were larger than expected within scale tolerances.
Now to get some 2.0gr loads for 32 S&W long done up.