October 19, 2025

Dillon 550 - powder measure

This same powder measure is used on the 650 and 750, and maybe other Dillon machines.

Someday I should weigh a series of drops to demonstrate how this powder measure repeats with various powders.

Adjusting the fail safe rod

I just finished loading a small quantity of .308 ammunition. I was getting terrible powder measure accuracy. I would see everthing from 43.5 to 44.5 and worse.

But I diagnosed the problem. I removed the plastic powder bin, which wasn't really necessary, but it allowed me to watch what was going on. Of course I emptied all powder. I also placed a cartridge case at the powder station.
The powder bar was not returning fully "forward" to pick up a new load of powder!

The answer was simple, namely tighten up the spring loaded adjustment at the bottom of the fail safe rod until the bar does move fully forward and the end of a cycle. Being able to watch the powder cavity with the bin removed made it obvious what was going on. It also made it obvious when the rod was adjusted tight enough, and it needed to be much tighter than I had it.

A suggestion online was to tighten it up to where it is just barely possible to fit a credit card between the coils of the spring. Mine does not need to be that tight to work properly.

Two powder bars

You could call these the pistol bar and the rifle bar. 
Extra Small - -3 grains
Small - 3-20 grains
Large - 20-45/50 grains
Magnum - 50+ grains
I only have (and have only ever needed) the small and large bars.

Upgrades from Armanov

Armanov (a company in Slovenia!) offer two fantastic upgrades for the Dillon powder measure. One is a knob that offers repeatable clicks, 50 per rotation. The other is a quick release that replaces the clamp with two bolts. Beware! A company called KMS is offering inferior clones of Armanov accessories, selling on Ebay and Amazon.
Feedback? Questions? Drop me a line!

Tom's Computer Info / tom@mmto.org