Loading for the AR-15 with the LEE Auto-Drum Powder Measure

Here on Ultimate Reloader you can count on a LOT of AR-15 content coming over the next year: everything from reloading .223/5.56, to hunting, a lot more with suppressors, and some custom AR-15 rifle action! In this post, I’ve got some great highlights including the LEE Auto-Drum powder measure, the RCBS Pro Chucker 5 progressive reloading press, IMR Enduron 4166 powder, Midsouth Varmint Nightmare bullets, my own custom Rainier Arms AR-15 build, and my first hands-on experience with Magnetospeed chronographs. Lots of exciting new experiences!

Loading .223 with the LEE Auto-Drum and RCBS Pro Chucker 5

Loading .223/5.56 for the AR-15 involves all of the “common” rifle reloading practices including measuring your brass length and trimming as needed. In addition, there are some special considerations for 5.56 brass like ensuring you’ve removed the primer pocket crimp, and selecting the right powder and powder charge- important considerations for both ballistic performance and reliable cycling/feeding.

For this loading session I wanted to try some new things, including IMR Enduron powder (see my intro post HERE) and the LEE Auto-Drum powder measure (see the kick-off post HERE). Here’s the full video experience starting with loading and finishing with some fun shooting and chrono’ing:

For those of you not familiar with the start-to-finish reloading process for .223/5.56, here’s the ideal process:

  1. Obtain once-fired military 5.56 brass (optional, can use .223 Remington to skip some steps)
  2. Clean brass
  3. Lube and size brass
  4. Measure and trim brass if needed (spec length is 1.760″, I trim to about 1.750″)
  5. Swage or ream primer pocket crimp (if once-fired military 5.56 that hasn’t been previously processed)
  6. Clean brass to remove lube (important to prevent bridging of powder in case necks when loading)
  7. Charge, seat, crimp (optional) on press
  8. Inspect and load into boxes

In the video above I’m loading processed brass, but am re-sizing and checking brass length with the Redding Instant Indicator to be sure over-length or non-processed brass doesn’t “slip through the cracks”. This is a GREAT setup:

Auto-Drum Pro-Chucker Stations .223

Here’s the per-station details:

  1. RCBS TC-series sizer/deprimer die
  2. Redding Instant Indicator (set to zero for 1.760″ length brass)
  3. LEE Auto-Drum powder measure
  4. Hornady bullet seater with optional micrometer stem
  5. RCBS TC-series seater/crimper die with seating plug removed

This is the first rifle loading setup I’ve tried where I use my “preferred pistol setup” that involves separate dies for seating and crimping. It’s great to be able to swap out bullet types and only have to worry about fine-tuning bullet seating depth. You can also tune your crimp level without messing up your bullet seating depth, very cool!

One note about setting up the LEE Auto-Drum is that you’ll need the appropriate LEE Rifle Charge Die as shown here:

LEE Auto-Drum and charge die

Setting up the LEE Auto-Drum for rifle reloading on a progressive press is very easy, here’s a breakdown of the steps required (assuming your Auto-Drum is setup for pistol loading when you start):

  1. Remove double-charge disconnector linkage
  2. Install LEE Rifle Charging Die in press
  3. Install large drum in LEE Auto-Drum
  4. Install Auto-Drum on press
  5. Fill powder measure
  6. Pre-set charge level (as shown in manual for LEE Auto-Drum), or setup charge on press as shown in video above
  7. Set rifle charge die height to fully cycle drum when press is at top of stroke with brass present in charging die station
  8. Validate and fine-tune charge weight with precision scale and once-fired brass with spent primer intact

It’s also a good idea to validate your “settle-in” charge on the press at set intervals until you reach a constant charge. Checking at intervals of 5, 10, 20, and 50 would be a good interval set. When loading rifle cartridges like .223 Remington you don’t need to worry about double charges because powder would overflow if a double charge was to occur (it will be VERY obvious, and involve some clean-up on your part!). Note that squib (empty) charges are still a possibility, so you’ll need to do a visual powder level inspection, use a powder checking device, or shake your cartridges (and listen to powder shake inside when loading your ammo boxes – this does not work for compressed loads!) to ensure you have safe ammunition.

This loading session was my first experience loading and shooting the new IMR 4166 Enduron powder, and I was very pleased with how it metered and shot! The combination of the LEE Auto-Drum powder measure and IMR 4166 was awesome. As seen in the video above, I was able to get 3-in-a-row identical charges, and the powder measure was very smooth with this powder. After accounting for settle-in, this measure and powder metered very consistently.


Here’s the load data for this session:

Note: This load data is for reference only. Always cross-reference with manufacturer’s load data. Ultimate Reloader is not responsible for errors or possible issues you may have when using this load data. Use at your own risk.

I like to load a test box of ammo before committing to a bulk loading session, and that’s what I did in this case. Every cartridge functioned in my AR-15. After this basic validation it was time to move on to some chronograph testing.

Magnetospeed Chronograph First Impressions

The 6.5 Guys have been using Magnetospeed chronographs for a while now, and I thought this would be a great opportunity to try one of these units out myself. Magnetospeed chronographs have some special mounting considerations (have to be strapped to muzzle or rail), but also have some unique advantages over traditional chronographs. One of these advantages is the fact that they don’t depend on lighting to function properly, something I’ve struggled with using traditional chronographs.

Here’s the results from a 5-shot test string using the ammunition loaded for this article:


The Magnetospeed chronograph had a 100% functioning rate during our testing. I decided to get a couple of Magnetospeed chronographs based on this experience, so stay tuned for more coverage of Magnetospeed (their latest chronographs!) here on Ultimate Reloader.

My custom Rainier Arms AR-15 Build

The AR-15 I demonstrate in this article is one of my favorite rifles. It’s light, handles great, is very reliable, has a great trigger, and looks awesome. I worked with the owner of Rainier Arms John Hwang to spec out the parts for this rifle, and did a build that turned out great!


If you all are interested, I’ll do some follow-up content on this AR-15 build! Just let me know.

The AR-15 platform is awesome. It’s a great rifle platform for the DIY’er, is an ideal all-around range rifle, is a great choice for many types of hunting (more on that later), and is super for defending your home and property.

Anyone else loading .223 for the AR-15 with the LEE Auto Drum? Anyone loading .223/5.56 with IMR Enduron? I would love to hear your experiences, please drop a comment!


5 thoughts on “Loading for the AR-15 with the LEE Auto-Drum Powder Measure”

    1. I’m reloading using the Auto-drum for my AR-15. I am using CFE 223 and Everglades 55 gr bullets (version II). Both of my AR’s are home builds, Anderson lowers and PSA uppers (one 18″, one 16). My press is a Lee progressive

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