MEC Sizemaster: Unboxing, Overview, Loading 12 Gauge Shells

I can recall using my MEC 600 Jr. Mark V, and thinking to myself- it would be nice if this press had a priming system built in… Fast forward to today, and I found what I was looking for with the MEC Sizemaster. It also has a powerful collet sizing system which reminds me of the MEC 9000‘s collet sizer- an added bonus! Let’s take a look at the MEC Sizemaster from uboxing, to setup, all the way to loading 12 Gauge shells! (I love these stories)

What’s In the Box

Here’s what’s included with the MEC Sizemaster reloading press:

  1. Powder reservoir
  2. Shot reservoir
  3. Primer tray (new primers)
  4. Spent primer tray
  5. Owner’s manual, basic reloading manual, catalogs
  6. Sizemaster press assembly
  7. Mounting bolts and wing nuts
  8. Small parts: Allen key, powder bushings (3), Priming system parts

All you need to add in order to load shotshells is powder, primers, wads, and hulls!

Assembly and Setup

Setup and assembly is easy and straightforward. There are just a few steps to complete before you’ll be ready to load:

  1. Obtain components and load data (you’ll need to know which powder bushing to install using the chart in the press manual)
  2. Mount the press to your bench or to a press mount. I used theĀ Precision Reloading Oak Baseboard with 7″ Aluminum Quick Change Brackets
  3. Insert priming donut and spring into priming cup, drop into station #2
  4. Remove wingnut from primer tray, slide onto primer drop tube post, attach wingnut, attach pull chain to bracket (with four links dangling)
  5. Install appropriate powder bushing
  6. Install powder and shot reservoirs
  7. Load primer tray with primers
  8. Load powder reservoir with powder
  9. Load shot reservoir with shot
  10. Load hulls and wads into bins next to press
  11. GO!

The above picture shows the priming system loaded and ready to go. Notice the spring steel strip at the bottom (a part of the selective priming system). It’s easy to load primers, just place the cardboard tray on the priming system, remove the cardboard, and then lift off the plastic tray. Voila- your primers are loaded!

Loading Shotshells with the Sizemaster

Loading shotshells on the Sizemaster is easy- the shell makes its way through multiple stations, each with a specific purpose:

Here’s what happens at each station:

  1. Sizing and de-priming
  2. Priming
  3. Powder charge (first stroke), Insert wad then drop shot (second stroke)
  4. Start crimp
  5. Finish crimp

A note about station #4 above, the MEC Sizemaster includes both 6 pleat and 8 pleat crimp starters. These crimp starters are super-easy to swap, you just pop it off, and then pop another one on (all with a simple push or pull). Once you get into the rhythm, the whole process goes really fast!

Here’s the complete spread of equipment and components that I used for this loading session:

Here we have:


The MEC Sizemaster feels like the familiar MEC 600 Jr. Mark V, but better! I feel it’s worth the incremental cost because I love how this press works. If you’re looking for shotshell reloading gear, please visit my friends over at Precision Reloading- they have the Sizemaster, and all of the supplies I demonstrated in this post/video (see links above).

But Wait, There’s More

If you liked what you saw in this post, I have great news- I’ve teamed up with both MEC and Precision Reloading to give away an entire MEC Sizemaster reloading outfit (including components) and will be making an announcement very shortly about how you can enter to win. Make sure you’re subscribed!

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4 thoughts on “MEC Sizemaster: Unboxing, Overview, Loading 12 Gauge Shells”

  1. Gavin, I purchased a Mec Sizemaster about 5 years ago. It’s a great press/simple to operate and produces uniform high quality shot shells. I enjoy shot shell reloading even more then metallic reloading.

  2. I used to reload for skeet and sporting clays on a Sizemaster.. I made my share of mistakes of spilled powder and shot, but I loaded a couple thousand of shells successfully. After a 20 year hiatus, and finally retiring, I am once again getting back into shogun sports and looking for a reloader. I’ve looked at high end progressive presses, but there’s something about the pleasure I had loading on the Sizemaster, slow as it is by comparison, that makes me want to buy another one!

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