Apocalyptic Prepping

Sizing Down 5.56 or .223 Brass

It’s really hard to find 300 blackout right now. I’ve found 2 boxes since the pandemic started and I bought them both, and I paid about $2 per round. It was all copper hunting rounds, so they were premium anyways, but I haven’t seen any since, and I go to 3-4 different gun stores about twice each week. If you’ve got primers, now is the time to be reloading. Reloading saves money, and it makes it possible to shoot when stores don’t have the ammo you need. Making your own brass is a great way to make yourself independent from these market fluctuations. According to my research, you can make 300 blackout brass from just about any cases derived from the parent .222 cartridge.

Which Brass I Use to Make 300 Blackout Cases

I haven’t noticed any difference between 5.56 or .223, and use both In fact, I’ve even used .204 cartridges as well. I try to identify .223 casings with imperfections that most would consider acceptable with form firing or just tossing. The dented cartridge below could probably be form fired, but why mess with that, especially for how plentiful .223 and 5.56 are? I’ve got a few thousand, and know several ranges I could go pick up more if I wanted. This type goes into the conversion bin to be made into 300 blackout.

My 300 blackout I load to primarily be used for close range situations. I don’t regularly shoot it over 100 yards. Because of this, I am not picky about identifying one specific cartridge brand to use. I haven’t noticed any significant accuracy differences, and my groupings are satisfactory. If you see more accuracy fall off you may want to consider using just one brand. One article we read said the writer only used Lake City 5.56 brass for consistency and quality. I’m not as particular. I haven’t had a brand or head stamp that hasn’t worked well for me in either 5.56, .223, or .204.

Size Without Decapping Pin

The first step is to remove the decapping AKA depriming and sizing rod from your die. Lube your cases and run them all through the die. We use One Shot case lube. It’s quick and easy.

Afterwards, your brass will look like this. I put it next to an unaltered 223 case for comparison. Some people skip this step, but this was the way I first learned. It also makes the amount you cut in the next step smaller, which I appreciate. Having them sized like this makes it easy to just eyeball gauge how the process is going and if you’re cutting off too much or too little in the rough cut stage of the process. I like to use an overabundance of caution when I’m doing any reloading, and sizing before rough cutting is just another way I try to incorporate safety when making 300 blackout cases.

Rough Cut

Next I use my makita grinder to rough trim the cases. I drew a line on top of my vise and then stuck some rubbery foam pads to the vise to hold the case without disfiguring them. Make sure you wear safety glasses. I caught one brass flake in the eye. You don’t want that.

Trouble with RCBS 300 Blackout Dies Not Seating Bullets Consistently

Some people also use a jig and and a cut off saw. I considered going that route, but I reload once fired 300 cases, and the converted 223 and 556 cases hold up pretty well. If I was cutting hundreds at a time, I’d get the jig and cut off tool. As is, I like that my grinder has multiple purposes, and it gave me an excuse to upgrade my grinder. The cut off tool and jig are more precise though and speeds up the next step. I actually compare the two methods of cutting 556 brass for forming 300 blackout in great detail in an article about My Setup for Cutting 223 to 300 blackout. The video below will also give you a quick look at the cut off saw method though.

Jig from Zep Reloading

They have a jig specially made for this type of work. It’s available from Zep Reloading who really ought to send us a jig to review (No, we don’t believe in subtlety). This method is a bit quicker than the method I use, but honestly I don’t cut enough yet to justify getting the cutoff saw and jig.

Trim

Next you trim just like you would with any other case. You should have more to trim than you normally would though. A drill attached case trimmer is easier here, but we feel this type is more precise, leading to more consistency and better precision.

Debur Inside and Outside

It’s now the right case length, but there usually a scrap brass bur both inside and outside the trimmed case mouth. I use the Lyman hand tool for this, but I take the tool head and attach that to my drill. It’s quick and easy. I want the nice electric case prep tool, but I also want the ability to do all reloading without power. I may get the electric case prep tool later, but it’s pretty quick in the drill. Debur the inside and outside.

Lube, Size/ De-prime

At this point you’ll need to remove the old primer. You could do this at the beginning with a .223 die, but it’s easier in the 300 die. I also have a lingering worry that the case size will change through all the trimming and work done. I haven’t seen any evidence this happens, but I feel better about it. Again, I like to double check and triple check my reloading work. Truth be told, I also usually only want to have one set of dies out at a time. I try to claim that this is for efficiency and being organized, but it could also be laziness.

Ream Primer Pocket

Again, I use the Lyman case prep tool. 5.56 and some .223 brass have a military crimp around the primer that needs to be removed before the primer is added.

Tumble

Yes, this is a second tumble. After all the cutting there is a lot of brass dust and brass flakes. I didn’t always tumble them a second time, but I had a jam and in taking it apart and cleaning it there was a lot of brass dust throughout. After tumbling a second time, I haven’t had any issues with that. As far as performance goes, I haven’t noticed any difference between the sized down and factory cases.

Lastly, I honestly don’t know what the norm is to say- is it 300 blk, 300 aac, 300 blackout? The whole 300 AAC Blackout? What’s your preference? Let us know in the comments below. We usually just say 300 blackout. Happy loading and shooting.

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