Arredondo Powder Bar testing.

I'm sure many of you know about this product.  Yet it was new for me, and I was asked by Lee Love of UniqueTek to provide some feedback once I test it.  I though that sharing my findings with forum members might be beneficial as well. 

Preface to the subject, - when I started reloading years ago, variations of powder drops drove me of the wall.  Loading on Dillon's XL650 plus / minus 0.1 of a grain or even more than that was pretty much a norm.  I identified number of components on two of my 650 presses that were contribution to such variations.  OEM powders bars, threads on adjuster bolts and powder bar inserts  were major contributors to the variations.  I've addressed these issues by taking several steps before any new powder measure / tool head is placed in ammo production on any of my presses.  I use wooden dowel sized for internal dimension of powder bar housing with 200 grit sand paper to make sure that bottom of the housing is flat.  I sand top and bottom of each powder bar running it over same 200 grit sand paper on flat metal plate.  I drill and install 8x32 set screws that allow for locking powder bar insert one proper powder charge setting is identified and set.  And of course, I immediately throw away OEM adjuster bolts and replace them with my own.  In combination with other steps I took, I'm pretty happy with accuracy I derive from what I have, - with powders like N310, BE, WST +/- 0.04 gr. variations in powder drops, which translates into sub-10 SD while testing ammo with LabRadar, is pretty much a norm.  So one would ask why bother with something else, why Arredondo bar.  Well, firstly I like tinkering with things (i.e. using Mark 7 Powder Measure on Dillon's presses, - another recent project of mine).  Secondly, and that is what drove entire project, - dropping small powder charges.  And I mean small like 1.4 - 1.7gr., or anything below 3.0gr for that matter.  I'm sure, those of you who load 38/32WC and 32 ACP know what I'm talking about.  With that said..............

First thing I noticed when Arredondo bar was extracted from packaging was what looked as a bow.  Placing bar on the flat surface of my office desk confirmed visual, - there was slight bow.  My first though, - hm..... this doesn't look good.  I anticipated the need for running this bar over my sand paper thing.  Then I though, it is made of plastic (nylon to be exact), let's wait.  Then I looked at insert.  Leaving aside that it required some effort to make insert stay in parallel with rest of the bar, - it was tilted slightly down and had desire to go this way on its own, I saw gaps between insert and body of the bar.  Not very promising visual either.  UniqueTek's Micrometer adjuster was/is known quantity for me, I have it on couple of my tool heads for more than dozen years in combination with Dillon's OEM bars, - it is good thing provided bars are prepared as I described above.  I then proceeded to setting up new powder measure with Arredondo bar and started loading measuring every charge...... 300 rounds.  It didn't look promising ...... in the beginning.  I've seen deviations in 0.10 - 0.16 grains, and predominantly towards plus charge.  I also notices some drifting in micrometer (placed two corresponding dots with a Sharpie on the body and thimble of the micrometer, so I can see if it moves).  And I saw some powder spilled (which I expected based on the initial visuals).  However somewhere at the 30-40 rounds mark I started seeing some improvements and powder drops became way more consistent and accurate.  At about 60-70 rounds mark most charges were within my customary +/- 0.02gr (which is what my GemPro 250 scale can detect) with occasional up to 0.06gr deviation.  Definition of "occasional" here is one in a dozen drops, which is quite good IMO.  And such deviation most likely doesn't come from powder bar.  Variations in brass and pressure in 5 stations, and variations in powder flow are the most probable causes for that.  I didn't have chance to test resulting ammo with rest.  However I tested it shooting hands free, and it was consistent based on what / how I felt. 

After I was done loading, I removed bar from PM and inspected it more closely.  It is "settled".  I mean, bow returned, but with applied pressure bar flattens very cleanly with no gaps.  And the most interesting thing is the insert.  Apparently internal walls of the bar and outside surfaces of the insert are slightly canted providing for good adjustment of the gaps.  I still think, that it would be nice to have option to install small set screw for sure locking of the insert.  However current design doesn't allow for it.  My conclusion is that Arredondo bar was actually quite good out of the box without any additional work done on it.

AP

I have one as well as the Dillon extra small powder bar. To be honest, once they are calibrated (I use the UniqueTek micrometer too) I don't find any real difference. I had a (far too) long post on the subject a few months ago. For me the biggest changes I made for accuracy were being consistent in actuation, a properly fitted powder baffle and polishing the inside of the powder measure funnel. The anti-static ground cord came about next. With all that in place when I can be bothered to measure I rarely get anything greater than +/- 0.04gr.

In pursuit of point (i) I've been thinking about an automated actuator - so far it hasn't seemed worth it.