Downloaded 223 in AR

[ohell]

I’ll go ahead and answer the question…. because it’s there and don’t want to pick up another caliber  

Anyone around here ever go down this road?  
Not looking for subsonic, that an’t going to happen and I can borrow wife’s bolt action 223 if I want single pew.    Before I ream gas port on decent 12.5” carbine length I think I’m going to pick up cheap pistol length gas port 10.5”, seems like the better option
 

             

[gregintenn]

Have you considered an adjustable gas block? You might still have to drill out the port. I dunno.

[Alleycat72]

I've run a subsonic ar15 without modification. It was suppressed and the ammo was a bit special. 

[Alleycat72]

100gr to 112gr round nose and rl15. Had to be 16" or less. The real stuff is 150 gr tungsten.  That will run in anything. 

[MP5_Rizzo]

16 minutes ago, Alleycat72 said:

100gr to 112gr round nose and rl15. Had to be 16" or less. The real stuff is 150 gr tungsten.  That will run in anything. 

Was OAL of this special ammo still magazine feed or single round load?

[ohell]

Atomic Tactical makes 112 grain subsonic 223 that cycles on YouTube.  Expensive. Rifle length 1:7 barrels appear to lower keyhole frequency.  Wild ballistic gelatin results 

adjustable gas won’t increase pressure vs good non adjustable.  But yes I’ll be using from the other setup before wasting more $ then I need.  Using superlative armsGB,  faxon LW bcg and yellow to white springco.  Assuming changing to pistol length gas port is better option - access to higher pressure and +1” dwell time in the 10.5”.  can only find in 1:7 twist which isn’t preferred, 

Trying to do pistol barrel length 5.7x28 to under with various bullets- varmint to slower 62 grain plinker. Powder option right now limited to 5744, maybe try H4895. I’ve never used fillers and don’t need with 5744 but may need to look into fillers on some powders

figured someone here was casting 223 and had been down this path.  

Edited January 6, 2022 by ohell

[Alleycat72]

7 hours ago, MP5_Rizzo said:

Was OAL of this special ammo still magazine feed or single round load?

Ran through a mag and an 11.5" full auto. 

[ohell]

adding update after two attempts over 9 months.  Maybe someone else is curious so posting.  
 

First-wasn’t happening with carbine gas port.  

**Do understand for safety - this setup is dedicated to this load, mainly by buffer.  Also dedicated to my assembly and bad things could happen, loads outside anything I could find published; even looking on random internet forums**

Second- Only 223 off shelf barrel I found with decent dwell and pistol gas port was 10.5” BCA 5.56 1:7.  using RTB nitride LM bcg, SA adjustable gas block 21 clicks which is one click into bleed off to extend life but will swap over to non adjustable after today and grateful it was there for tuning, springco yellow and two weights out of carbine buffer for 1.6oz total, chinesium flash forward 1.5” long with center and perimeter holes.  I have more $$ in my cmmg 22lr bolt/barrel/mag purchase. 

Expensive AA5744 was in top three and available so AA5744 it is.  Speer vol? has reduced 223 loads for 5744, but nothing over 55gn bullet and not semi auto friendly.   50gn Speer varmint and unknown 62gn soft point. OAL was just off rifling and close to mag length because I didn’t want a lot of jump/pressure loss.  I’ll venture into 70gn after today but mindful fast rifle powder with heavy bullet = no published loads for a reason. 

Wanted heavier then the 50gn and some success with 50gn, but the 62gn was soft like ten ply and allowed cycling at lower end.   Cycling and bolt locking back with 62gn ranging 11-13gn loads. 11gn charge was the reliable bolt lock floor, four o’clock brass. Stop here or change something like barrel extension or ream port, Ran up to 16gn of AA5744 with 62gnSP but needs standard weight buffer back in at 14gn due to brass at 1 o’clock and no lock back using standard weight till 15.5gn.  Hodgdon web site starts 55gn bullets at 16.8gn, but aa5744 is not too position / case fill sensitive.  next will be crony data and print on paper with oal adjustments. It will hit steel at hundred yards.  Figure about 1600-1800 ft/sec extrapolating from reduced loads with 55gn. 
 

[ohell]

Not much interest/conversation on this forum. Updating thread to close out here but continuing to play with 223 in 22wmr or 5.7 range without expense of another platform.  
Changed buffer to the short strike industries pistol tube with guts that come with it, rest as above. Cartridge OAL was shortened to recommendation in Speer #14. 
Looking for reliable bottom and ejection isn’t forceful but consistent with fast fire.  Brass was mixed demil because 2022, sorted head stamp for groups below.   Plenty of room up from here and shooting 62gn at 2440fps AA2230 out of this setup with acceptable timing so not a dedicated setup like buffer mod mentioned above. Put on paper at 100 yards, no magnification and good results. 

Unknown 62gn BTSP 12.5 gn AA5744 ten shot avg 1510 es33 sd9

bump to 13gn nine shots avg 1554 es23 sd9

Speer 1053 70gn 13gn AA5744 five shots avg 1499 es16 sd7 

Had some trouble with oal on Speer 1029 50gn but with SI pistol buffer noted above 13gn of 5744 velocity 1615 fps  cycled fine on ten rounds at shorter oal but run out was jamming so had to sort to get through, pulling rest for retry  

will slowly try other runs and tweak   At the cost of AA5744 the reduced charge isn’t saving anything. But good option for semi auto youth loads  

 

 

[Quavodus]

I've loaded a few  "light".223's in the past but, not for my AR. I shot them in a Savage 110. I might try some sometime.

Edited November 17, 2022 by Quavodus