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Wow.... looks easy enough
For give my ignorance.... learning something every day...
I was gonna start hunting for.300 blk out brass after finding a.300 die set but remembered they were cut down.223.... which is nice because I have enough to go around.

Remove inside neck sizing/de prime pin.... cut it with saw little bigger.... trim... deburr..

Straight forward or do I need to know something else?
THX
 
Not straight forward. Brass thickness is the problem. Most 223 will work. Many 5.56 will not. If you load any projectile with too thick a neck, it will not chamber and you WILL have to mortar the round out. Your options are stick to 223 marked brass, or be prepared to deal with neck turning and military crimping. It is VERY labor intensive.
 
Converting 223 --> 300aac is labor intensive, and it can be done with success. Brass thickness is a large part of the issue. Some cases are simply thicker than others and they wont chamber properly after being cut down and resized.

I used this page as a reference and pulled brass that had previously been measured and tested with this process. My success rate was 99% when starting with sorted brass according to this information:
LINK

You will need to do all the other fun stuff once your brass is trimmed... but it can save cash and may be the only option for some if 300 brass isn't available.

Do 10 to start out with start to finish then go fire them. If you're success and confidence is high after that go trim 500 ;)
 
Converting 223 --> 300aac is labor intensive, and it can be done with success. Brass thickness is a large part of the issue. Some cases are simply thicker than others and they wont chamber properly after being cut down and resized.

I used this page as a reference and pulled brass that had previously been measured and tested with this process. My success rate was 99% when starting with sorted brass according to this information:
LINK

You will need to do all the other fun stuff once your brass is trimmed... but it can save cash and may be the only option for some if 300 brass isn't available.

Do 10 to start out with start to finish then go fire them. If you're success and confidence is high after that go trim 500 ;)
Thank you....
great resource...
just what I was thinking but backwards. I was thinking if it's thinner then I'd have splitting issues. I was hoping to i didn't need to look for my smallest swage.
 
FWIW, Sportsman's Warehouse carries .300 brass ($180/1000 as does Optics Planet.
That might be an easier course to take starting out.
 
FWIW, Sportsman's Warehouse carries .300 brass ($180/1000 as does Optics Planet.
That might be an easier course to take starting out.
Sportsman by me is empty
I don't see it on optics planet right now
Thx though... I'll keep an eye out
 
Ive converted many thousand of rounds to 300 BO. Mostly LC 5.56 and no, you dont have to hammer anything. The only shells Ive ever found that you ABSOLUTELY have to avoid is Philippine Armscorp brass. It is definitely too thick in the cross section and will lock a chamber up.
 
harbor freight mini chop saw, ebay 300blk conversion jig for the chop saw,one shot case lube, a die set, a case trimmer, deburr and chamfer. annealing them wont hurt either.

run your brass thru a tumbler or wash them off to get excess brass dust from the saw off of them before you lube them and start to resize.

@Kruel J is correct. ive probably converted 5000 or so 223/5.56 into 300blk and shot just as many that have been converted. i pay no attention to headstamp while doing so. never had a problem. not one.


when i sort out my 5.56 i throw away PPU. so those get weeded out before i convert to 300blk anyway. i also throw away PPU 7.62 brass. its way too hard to resize on my press.
 
I'm another one that has converted thousands of 223/5.56 without paying attention to headstamps. Never a single problem.

I don't load to max and my last stage is a Lee FCD.
 
Originally compiled by tlee_20, updated with user reports. In general, the wall thickness around 1.360 inches from the base will determine success or failure. As a rule of thumb, if the wall thickness is greater than 0.014, there may be problems with the loaded diameter of the neck being too large to chamber easily.

Neck thickness data:

Factory Blackout brass

Gemtech (factory 300 BLK) - 0.011"
PNW Arms - 0.011"
RP - 0.010"

Converted brass

Good:

ADI - 0.012"
Aguila - 0.012"
A USA - 0.012"
FC - 0.013/0.014" [Note 1]
GFL - 0.012" (Fiocchi) Some GFL may have different thickness
HB - 0.013"
Hornady (223 headstamp) - 0.011"
Hornady (nickel 223) - 0.012"
IK03 - 0.012" [Note 4]
IMI - 0.012" [Note 4] Listed on both lists, but seems like more often good than bad.
IVI - 0.013"
IVI ('85) - 0.012" (runs great)
LC - 0.011"
LC (converted blank) - 0.012"
M193 - 0.011/0.012"
Norinco 223 - 0.010"
NOSLER - 0.012"
PERFECTA 223 rem. - 0.012"
PMC - modern "bronze" and "X-tac" are good, older PMC with small letters may have problems
PS - 0.011/0.012"
PSD - 0.011"
RA - 0.013"
RA ('69) - 0.012"
RP .223 - 0.011"
SSA - 0.012"
TAA - 0.013-0.014" [Note 4]
Tula - 0.0115"
TW 67 - 0.012"
TZZ - 0.012"
WCC - 0.010/0.011" (Some less common WCC headstamps run thicker, but the majority are good to go)
Winchester - 0.011"
WIN NT - 0.011"
WMA - 0.011" (Winchester Military, equivalent to WCC)


Thick neck wall, bad without neck turning:

AB 556 - .015" to .016"
ATI - 0.015" [Note 3]
CBC - 0.014/0.015"
CJ6 - 0.015"
CJ 8 - .014"
DNL - 0.016"
FNM - 0.016" [Note 3]
FRONTIER - 0.015"
GECO - 0.015/0.016"
Hot Shot - 0.014" [Note 3]
HRTRS ( Herters?) - 0.017"
ICC - Reported as bad
IK03 - 0.015" [Note 4]
IMI - 0.015" [Note 4]
IVI - 0.015"
KFA .223 REM - 0.015"-0.019"
L2A2 - Reported as bad
MKE13 - Anecdotally reported as troublesome
MPA - 0.015"
Norma - 0.015"
NPA - [Note 3]
PMC (old headstamp) - 0.015"
PMP - 0.015"
PPU - 0.014/0.015" [Note 3]
RAM 223 - .014"
RORG - 0.015"
RWS - 0.014-0.015"
S&B - 0.015/0.017"
SADU - 0.014/0.015"
TAA - 0.013-0.014" [Note 4]
T - 0.015
SADU 5.56 - 0.014-0.015"
Wolf Brass .223 - 0.014"

General notes:

There's no consistent difference between "5.56" and "223" when it comes to brass.
 
All good info.
Only problem I've had was due to a case neck that didn't get adequate lube. Resulted in a fifteen minute break while I extracted the stuck case. Oop's :oops:
 
Last Edited:
My only issue is before the first fire forming where the shoulder isn't as square on converted vs made brass.

After shooting once, no issues and it does well.

I've converted lots myself too. No real problems.
 
I started making my own brass probably over 8 or 9 years ago when the AAC .300"Blackout was becoming popular and my setup worked well.
I had difficulty getting powder for the longest time but I was able to get plenty of it eventually.
There are better jigs and gauges now but I used JB weld to make a mold for the HF mini cut-off saw that held my brass.
I put a cordless drill on my RCBS case trimmer and deburred them to the SAAMI spec before tumbling.
I got a lot of .223/5.56 once fired brass from a buddy of mine and I made a lot of .300 Blackout brass.
I found several sources that were making it back than and I get some of that too while stocking up on primers and 30 caliber bullets.
Little did I know that this project would become a big project and basically a little goldmine right now.
I still use only my Rockchucker single stage press and I can make really nice ammunition if I want to do it.
Fortunately I took advantage of the "salad days" and bought a lot of boxed ammo as well.(even Walmart had it)
Every show and every shop, I'd try snag a box or two, it was really cool stuff back than.
To the newer guys getting started, this is a big project and it took me years to get things going and eventually start cranking out quality ammo that was made by hand, including the tedious process of making perfect and cool looking Blackout brass.
I see an empty on the ground and I will pick it up if I can, these little rounds are very special to me.
 
Make away! - Just monitor the headstamp so you're using one not too thick. Personally, I just moved to Lake City 5.56 mil brass and have never had a problem to date.

I run them a bit differently. I use a Dillon 1500 case trimmer with a .300blk die. Neck resize die and done. No deformation, small burr however that needs to be touched up still.


But running them on a Dillon 1050 with an auto-drive, I can auto-feed the brass, universal de-prime, swage the primer pocket, trim down, reform and neck size. It just spits finished .300blk brass out.
IMG_3061 3.JPG
 
I started making my own brass probably over 8 or 9 years ago when the AAC .300"Blackout was becoming popular and my setup worked well.
I had difficulty getting powder for the longest time but I was able to get plenty of it eventually.
There are better jigs and gauges now but I used JB weld to make a mold for the HF mini cut-off saw that held my brass.
I put a cordless drill on my RCBS case trimmer and deburred them to the SAAMI spec before tumbling.
I got a lot of .223/5.56 once fired brass from a buddy of mine and I made a lot of .300 Blackout brass.
I found several sources that were making it back than and I get some of that too while stocking up on primers and 30 caliber bullets.
Little did I know that this project would become a big project and basically a little goldmine right now.
I still use only my Rockchucker single stage press and I can make really nice ammunition if I want to do it.
Fortunately I took advantage of the "salad days" and bought a lot of boxed ammo as well.(even Walmart had it)
Every show and every shop, I'd try snag a box or two, it was really cool stuff back than.
To the newer guys getting started, this is a big project and it took me years to get things going and eventually start cranking out quality ammo that was made by hand, including the tedious process of making perfect and cool looking Blackout brass.
I see an empty on the ground and I will pick it up if I can, these little rounds are very special to me.
Sounds like you are still in reverence for the craft... I hope to walk that path.... making decent/excellent ammo from my single stage. I was advised to keep it real slow in the beginning even though the turrets look stinking SICK. I started this hobby to produce just one more expensive cartridge, but thought I might see how accurate my other weapons could be. A friend at the range said..." I may not really be saving that much or any money reloading but I like shooting my own stuff"... I liked that. Think this is gonna help slow my shooting down too.... I like that.
I had a decent amount of.223 but couldn't find any.300 brass..... hence seeking knowledge and advice.
 
Make away! - Just monitor the headstamp so you're using one not too thick. Personally, I just moved to Lake City 5.56 mil brass and have never had a problem to date.

I run them a bit differently. I use a Dillon 1500 case trimmer with a .300blk die. Neck resize die and done. No deformation, small burr however that needs to be touched up still.


But running them on a Dillon 1050 with an auto-drive, I can auto-feed the brass, universal de-prime, swage the primer pocket, trim down, reform and neck size. It just spits finished .300blk brass out.
View attachment 835807
Very impressive equipment... maybe one day...
Couple resources I've copied here for selecting brass... thx to the forum...
I've got Lee Breachlock single stage, Lee Pacesetters..... waiting on Lee case length gauge, and or the Lee Quick trim die for the press. Just one box of bullets coming for now. I was lucky that I already had compatible power from my 12.7/42 cartridge.

I only have 3 cases of brass to choose from for now, head stamp....:
REM.223. FC
PSD. 20
LC. 19. (+).... circle with a plus sign in it.

So gonna be small time for awhile but I think I'm just seeing what I like the best out of all the different ammo I will try to make.
 

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