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I bought a set of Lee 300 AAC Blackout dies so that I could build 300 AAC Blackout cases from my too short and ruined .223 Rem cases.

It took me a while to get the process down on how to first cut the .223 Rem's neck off without making a complete mess and taking all day to cut them. I finaly hit on using my Dremmel tool with a cutoff wheel on it! 127 cases cut in about 20 minutes!

Next was getting the necking die to work right. I read somewhere that you have to anneal the neck area of the shell that softens the brass up so you can reform it without splitting the case. So I set up a pan of cold water and annealed five rounds just to be sure that it waw what I realy needed to do. Well, it wasn't the way o go as I noticed NO difference in forming them with cases that weren't annealed.

I did put Hoppe's gun oil on the bullet end of the cases before I loaded them into the forming die which more than helped get the brass reformed.

Next step was to cut the new 300 AAC Blackout rounds to length. The blueprint that I found at the AAC website said to cut them to 1/368" COL. I used my RCBS Shell Cutter that I motorise with my Sears Craftsman cordless 1/2" drill driver. The cordless drill makes cutting brass a 100% easer! After cutting all 127 cases to 1/370, I power deburred them with my cordless drill.

I'll post a picture of the finished brass when I get time in the next few days.

Just took this picture of my new 300 AAC Blackout brass that I made today.

H110 for powder.

Thanks to al for all of the information.

The Hodgdon websites's loading information is, to say the least, OVERWHEMING! I will follow their data to the letter so my reloading question was directed at "what works for you/personal experience with actually shooting 300 AAC Blackout rounds.

As for the length of the brass, I can always make them shorter but no longer so I fabricated them to the longest length.

I think the brass turned out very nice especially when you consider I've never "built" a round from one caliber to another. I did a lot of reading, a lot of asking, and "re-invented" the whell along the way to making them.

I did find that annealing the brass was unnecessary for my brass. Someone elses brass may have to be annealed to prevent cracking the cases.

Lubricating the mouth of the un-resized brass was a must do when resizing and cutting it to length.

I'm anal about measuring everything in this process as this is an entirely new endevor for me.

I have to say it is fun and rewarding! The end prduct looks impressive and I salvaved 127 pieces of brass that would have been sold for scrap.

I fogot to mention how I cut the .223 Rem cases so that they had only the body of the case & base but not the arear from the start of the neck forward. I used my Dermmel with a cutoff blade. It worked a lot easier than a hobby hacksaw, that's for sure. IF I were going to do many more rounds, say 500 or more, I'd put them in my lathe and use the cutoff tool which would make a cleaner cut.

Barnes 300 Blackout 110 TTSX all the way

Looks good, I think it's pretty neat making a totally new round out of an old case too. I started with my Dremmel also but quickly switched to a mini cutoff saw, nice clean cut and it's fast. I haven't tried annealing yet but my brass has only two rounds through them with no signs of splits. I did try some Sierra 110gr but they wouldn't feed reliably even at max length, so I'm sticking to 125's or 130's which were flawless. I think you got it down pretty good.

Those Barnes bullets are wicked! I wil be using then for hunting this year for sure.

I found some Hornady 150gr BT FMJs for cheap localy. Anyone have a good load for them using H110?

Gets some Speer 150 gr BT's at your hunting distances they should be an absolute hammer. With 16,8gr of Lil'Gun an a COAL of 2.100" I get 1915 fps out of my 16" CMMG.

That's the good news.

Now for the bad news.

I reloaded about 50 rounds and I've done something WRONG with them. Half of them won't allow the bolt to lock up. I think I've found what is wrong with them as I didn't set the Lee sizing die up correctly. I re-read the directions a dozen times and finally got it through my thick skull what they were talking about.

Understand that I am dyslexic so written directions don't work for me but oral ones do.

Now that I have the brass in specification, now I need advice on EXACTLY what the completed rounds should be.

Here’s what I have so far:

Part I

Re-reformed .223 Rem cases that are 1.368” COL.

The distance from the base of the cartridge to the beginning of the neck is 1.0700” nominal.

The distance from the base of the cartridge to the beginning of the projectile diameter is 1.102” nominal.

An primed but empty (not loaded) case now allows the bolt carrier assembly to go to battery whereas before I got the Lee forming die set, the bolt carrier assembly would NOT lock up!

Can I assume that the brass is now in specification?

Part II

For bullets, I have Hornady V-Max #23010 110 grain bullets. They are .935” long. According to the Hodgdon reloading data on their website, the COL minimum is 2.040”. That means that .263” of the bullet is seated in the case (2.040” - 1.360” = .672” - .935” = .263”). Is this correct?

I do NOT have a crimp die for a .300 AAC Blackout. The directions that came with my Lee die set give a part number of 90590. Do I need to buy that crimp die?

The reloading data on the Hodgdon website says that there can be from 18.8 to 20.0 grains of H110. I loaded 19.4 grains of H110 and all of the rounds that would lock up were fairly accurate given that it was VERY frustrating having MOST of my rounds not letting the bolt lock up!

I’ve since unloaded all of my rounds, run them back through the (now properly set) forming die and will be loading rounds after I hear from all of you that I’m on the right path to success or not.

As always, any and all advice will be greatly appreciated.

I applaude anyone who forms their own brass but think this option is easier for many of us.
I've reloaded approx. 500 units of this re-formed .223 and it works great, the price is right also!

http://www.blackoutbrass.com/

I'm the product of parents who lived through the great depression = I HATE to throw away anything that my have a use hence the .300 AAC Blackout formed from .223 Rem cases that I would have scrapped fits my "id".

I reloaded six rounds today and fired them from a five round magazine. One round failed to let the bolt go to battery. I think it somehow evaded my running them through the PROPERLY setup Lee resizing die. So now I'm going to have to audit all my brass AGAIN. Fortunately, all I have is about 170 rounds to inspect.

I like the .300 AAC Blackout that I built EXCEPT for the forend grip picatiany rails are hard on my hands. I may get some rail covers as I found a place that sells a set of four for under $15.

What little that I have shot it has shown me that it is sweet to shoot! I need to get some range time with it to get more confortable with it though.

I want to thank everyone for their input. All help and advice is greatly appreciated.

I bought a cheap-o little drillmaster chopsaw from harbor freight to cut my 223 brass to rough length, then run it throught the resizing die.
I found my reformed brass difficult to chamber after loading so I've started turning the necks down on my case trimmer and it seems to have corrected the issue.
That could be the issue you ran into with the one round that the bolt did not fully go into battery.