300 Blackout

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Trent

Trent

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Ok.. I had a bunch of AR lowers leftover from when I had my gunshop. So on a whim, I decided to build a dedicated 300 AAC blackout... (getting tired of 5.56 and want to experiment some.)

But ... I have no ammo, and I flat out refuse to pay the high entry fee of factory ammo / cases. :)

Before I get started, does anyone got experience (good or bad) or useful tidbits of info on converting 223 casings?

In particular, I'm looking for an .. expedient (fast) way of chunking out about 500 cases from 223 parents.

Also, not really relevant to the question above, but for some background info on WHY I chose this caliber. I already have a ton of 220 grain Sierra Matchkings on hand from 300 Win Mag shooting - I planned on this being a subsonic only gun, so it's built with a pistol length gas tube. This was an overriding factor in this caliber selection; commonality with stuff I already have; in this case, 220 grain bullets, a surplus of AR parts, AR magazines, and 223 parent cases.

That, and the novelty. :)

Thanks in advance for any help/advice!
 
I use a Dremel and cut at the shoulder of the 223 Remington. A jig as shown in the videos wold be more precise and maybe a bit quicker over all reforming time.

I also got a 300/221 Fireball (or is it 221/300 Fireball) trim die to do the preliminary forming and to be able to trim the case to the proper length.

Clean up the mouth and do final forming in the full length die then final trim.

Not difficult to do, a bit time consumiong.

As a side note, I am finding re-formed 223 cases have less internal volume than 300 Blk cases so adjust you loads accordingly if you switch between the two cases.
 
Chuck,

With the cost of factory ammo, I'm only going to shoot hand loads, and plan on working up the load starting 10% under what they list for the subsonic 220gr load. Thanks for the tip about the volume being different than factory, that thought hadn't crossed my mind. That would become relevant if I ever bought factory brass (likely, as sometimes I'm known to go the path of least resistance... and I'm a sucker for bags of brand new shiney things...)
 
Also, if 223 cases have less internal volume, then I would have to assume that the 5.56 MILITARY cases I plan on using will have even LESS than that. So that becomes even more relevant!
 
Trent said:
Also, if 223 cases have less internal volume, then I would have to assume that the 5.56 MILITARY cases I plan on using will have even LESS than that. So that becomes even more relevant!
Click to expand...

Not necessarily. LC 5.56 military cases typically run significantly lighter than WW 223 Remington commercial cases indicating that the internal volume of the LC cases is probably more than the WW cases.
 
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I chuck the .223 case into my cordless drill and then clamp it in a pipe cutter and let the drill spin the case and the neck portion falls off on the bench. I did a bunch like that. Worked fine.
 
I've made a couple of thousand cases using a 300/221 form die,sawzall and a file.
Run the 223 case thru the die use sawzall to cut off the excess and file to clean up,deburr inside and out and your off and running. I could make 75 cases an hour with the above method. There are folks on sites such as Gun Broker who sell formed brass for short money.
 
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Work down, not up!

I reload 300 blackout but I go supersonic.....From what I understand about reloading sub's you start a little over the load data then work down to just under supersonic velocitys. Starting 10% under a subsonic load data could lead to a squib and then to a "big problem"......just food for thought and i am by no means experienced loading subsonic.
 
M.Weier is correct, when working with subsonics it's better to work down than up, this is particularly important when working with jacketed bullets, they are not easy to remove when stuck in the bore.
 
Interesting, never thought about there being a difference with the approach to loading subsonic. Never done it before!

The thought of extracting a jacketed 220 gr 30 cal from a 16" barrel makes me cringe a little inside.
 
Trent said:
Chuck,

With the cost of factory ammo, I'm only going to shoot hand loads, and plan on working up the load starting 10% under what they list for the subsonic 220gr load.
Click to expand...

http://www.300aacblackout.com/

It says to adjust powder "down as needed."

Suggested subsonic load:

• R-P 300 AAC BLACKOUT brass
• Remington 7.5 primers
• 11.2 grains of A1680 powder (Adjust powder charge down as needed. Factory ammo is 1010 fps for 16" barrel)
• Case length is 1.368 +0.000 -0.020
• Sierra 220 MK loaded to 2.120 OAL (this length is optimal for reliable feeding from USGI magazines)
• Chamber pressure 21,100 psi.
 
Cost is relative. :)

This is a subsonic only gun, can't shoot supersonic out of it due to the short gas tube. Would do nasty things to my bolt.

I have 40K+ 223 cases, around 3,500 220 Gr. Sierra Matchkings (made a bulk order of 5K for my 300 win mag a few years back, still working though them). Also have powder / primers.

So cost to make my own is $0.

Subsonic is more costly; 220 gr bullets cost more.

http://www.midwayusa.com/product/85...0-grain-subsonic-open-tip-match-otm-box-of-20

A buck a piece is a bit much to swallow, when I have all the components sitting here. :)
 
Trent said:
This is a subsonic only gun, can't shoot supersonic out of it due to the short gas tube. Would do nasty things to my bolt.
Click to expand...

If your gas port is too large to shoot normal ammunition, you can get an adjustable gas block. I know you know this, but just saying it for others to hear. The gas port in my rifles shoots subsonic and supersonic with no adjustments.
 
Pricey, but looks like they'd fit the bill. Think I like the second one a better, ability to fine tune is always a good thing.. :)

One last item to order before I make a run at it; sizing dies. Any recommendations there? I've been partial to Redding and Forster over the years, but with this being a relatively new cartridge, I'm open to suggestions.
 
I currently use a Redding resize die with the 300 Blk.

I bought a Hornady set first. At the time, it was all that I could find. Then bought the Redding second. I forget whey I did not like the Hornady resize die but it has been retired after a short life.

I still am using the Hornady seater with 300 Blk.

I like Redding dies. I have been having issues with several different Hornady dies of late and will probably swear off them for a while.
 
Just note that the older Hornady Whisper(R) dies resize a few thou smaller than desired for 300 BLK brass. They fixed it on the Blackout marked dies.

The Lee seem fine. Crimp die is optional but only $10.
The Forster seem fine - best choice for bolt action ammo as they do the least resizing.
The Redding seem fine and crimp.
The RCBS seem fine. Not sure if it crimps.
 
rsilvers said:
Just note that the older Hornady Whisper(R) dies resize a few thou smaller than desired for 300 BLK brass. They fixed it on the Blackout marked dies.
Click to expand...

My Hornady sizer die is marked 300 AAC/Whisper so I guess it is one of the new ones. I still do not remember exactly why I retired the Hornady sizer die. Maybe just because i found a Redding set.
 
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