Converting .223 to .300 Blackout

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OldAFVet

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My son has dumped the task of loading for his .300 BO on me hand presented me with a bog of .223 cases to convert.

I've made .30 Herritt cases from .30-30 cases before, but that was pushing the shoulder back on the same diameter neck and then cutting the neck to size, The 300BO is pushing back the shoulder and opening the neck before trimming, a bit different.

Any 300 BO loaders out there who make their own cases with some tops so I don't trash a pile of cases?
 
Go to youtube and look at all the different video's on there. That's what I did before I started resizing .223 cases into .300BLK. Best thing I could suggest would be to get the mirco chop saw from Harbor Freight. That, and break out the shop vac. You will end up with brass shaving's all over the place. Once you have cut the cases down close to size. Cut them alittle long. Run them thru your sizing die(use lube). Once you have sized them, trim the cases to length. If you trim them to length first, when you size the cases, They can end up shorter than you want. It is a really process, just time consuming.
 
I'm not saying this is right but this is what I do and it works well for me someone else my have a better process....

Processing 300BLK Brass

Starting with brass ready to reload as 223 or 5.56
(ie) inspected, deprimed, cleaned, primer pockets swaged (if mil brass))

Do a small number of cases to start, maybe 5 to 10 cases:
Do each case as a batch: taking one case at a time through all the steps,
to get everything set and adjusted correctly.

1. Cut case to 1.365" to 1.370" - cutting the neck and shoulder areas off the case.

2. Debur the new mouth inside and out.

After Step 2, check case wall thickness with calipers. If over .0125 it will not chamber correctly once a bullet is pressed in. This is very important if you're using misc brass, and you'll start to see a pattern of which cases aren't going to work and you can skip trying to convert them. if you elect to use 7.62x39 bullets (typically .310" diameter), take the neck wall thickness into consideration = meaning that case neck wall thickness should be .012" or less.

3. Anneal

4. Lube cases.

5. Form in FL resize die.

6. Check case forming in a case gauge. Adjust size die as necessary.

7. Trim case to Trim-to-Length: 1.358"

8. Deburr the mouth inside and out, again.

9. Check trim in the case gauge. Adjust trimmer if necessary.

10. Clean cases of lube.

Once cases go through all the above steps and come out right,
go into "production" running the rest of your allotted cases as a single batch,
doing each step to all cases with occasional gauging to make sure everything stays good.
 
I tried the above methods and have reversed a couple of steps as I think it works better for me.
I run the 223 cases up the sizing die (no decapper) first, before cutting to length. I find that if I cut to length (cut long for trimming) that there is a burr on the cut that has to be removed or you take a chance on mucking up the sizing die. By sizing first you eliminate this step and any complications.

Next I use the HF chop saw with a jig made to cut each case at a specific spot. There are a number of people who make these jigs. My first one I made out of some wood trimmings and it worked fine, then I bought one of the above made jigs.
After they are cut then I trim & chamfer and then I might run them thru the sizer again with the decapper & expander ball if needed. They normally don't grow in this step.
I annealed one batch but found the cases are very short and you risk making the body & head too soft. You could get a 650F templistick (welders supply) and dunk when it starts to run but without something to gauge temperature at the shoulder I wouldn't anneal.
Also, stay away from thicker cases such as some PMC and foreign military. Most people like LC and WCC and I have heard that Federal is soft so the primer pockets don't last long. I use a .1745"- (IIRC) pin gauge to check them. The rest is straight forward loading.
 
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I haven't made 300 Blackout brass, I made 30 Mauser brass. This is shorter, so if it worked for me it will work for you. Using FL sized de-primed military brass with the crimp removed (case lube removed also). I used my table top band saw I cut off the case at the base of the shoulder. Then without lube, FL size in 300 Blackout die. I use a Forester case length trimmer and trim to length and use a .308" neck ream as the trim guide (this is only brand you can do both in one step) to ream neck inside diameter. Remove any brass timings from inside case prime and load to specs. The lower shoulder angle may be a little round, but will work and fire form to chamber. After I was set up on the workbench, I formed 200 30 Mauser brass in a few minutes over 1 hour. Speed was of importance to me and I killed a few brass in my haste, but back then used mil brass 4 cents or less apiece. Have fun. Ivan.
 
Is the problem of the cases being too thick to chamber because of the case body too thick, or that the reformed neck is too thick? I have a .30 neck reamer from my .30 Herritt days that should reduce neck thickness.

I will run thru Youtube first, but boy wonder hasn't come up with the dies as of yet.
 
The neck will need thinned. Reaming is quicker than neck turning the outside. It is funny; when you reform cases, "THEY" say ream the necks. But when prepping brass for bench rest, "THEY" say to turn cases. I have equipment for both and can tell you reaming is a lot quicker. My 22 BR brass are the only set of cases I needed to turn; They wouldn't chamber the necks were so thick. My 6 mm PPC is a no turn chamber, when my friends have rifles built that require case reforming they always go with "No Turn" necks. Ivan
 
Don't 'they' generally say that because when you ream the inside your just making the necks thinner all the way around and if the hole is off center, one side of the brass will still be thicker than the other side, just like in the original case. However if you turn the outside (centering on the mouth) then the brass should be the same thickness all the way around (theoretically) and should provide uniform tension/release thus better accuracy for bench rest purposes.

I agree, all I do is ream if needed.
 
125JHP, I think you hit the nail on the head. But for this conversion, I think reaming will be quick and efficient enough. I really like the L.E.Wilson case length trimming tool for quality case trim work. When I do a batch, they come out within .002" for the whole group of brass. My second favorite is the Forester and/or Forester Classic, they turn out batches in the .003-.004" range. The worst I've ever used was the RCBS power case trimmer, it produced groups of trimmed cases that varied up to .015". The problem is in the way cases are held in place, it can be very inconsistent in the pressure of grip. But when I was converting 223 brass to 30 Mauser brass the ability to trim to length and ream neck thickness at the same time and use a drill for power all at the same time, was a God send. I mounted the trimmer to a piece of 1 x 4, and mounted vertically in a vise. I got a system going that took only 4 or 5 seconds per case. Out of over 225 cases I lost 5 or 6 cases to out of square mounting the case in the trimmer. But like I said before; I did over 200 cases including cut off necks, form, and trim in 1 hour, That means I touched 10 cases (or more) a minute. The only thing pretty about it was, I was done before most people could look up the numbers and place the order at Midway. I use the brass in my C-96 and they work fine. A friend of mine later made a batch of 100 for a CZ-52, but found that lost brass was a issue, and went back to surplus ammo. I don't have a Blackout upper for my AR, but I have a brass catcher for my 223 and 22lr uppers. Have fun. Ivan
 
Yeah, lost brass is an issue... ya gotta be quick to catch them brass before they're outta reach.
I can never get that bushel basket to stay on my AR.
 
I have one of those Cladwell brass catchers, and that thing acts more like a brass deflector than a catcher. I tried several different angles before I got a bit heated and took it off.

As far as cutting down the brass, I have not run into any issuses with PMC brass(yet). Maybe I got lucky.
 
y9eta5a2.jpg

This homemade brass catcher was well worth my time

Sent from my XT1055 using Tapatalk
 
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