converting a .223 upper to cycle sub-sonic rounds

Rusty
We Band of Brothers!
DRSS, NRA & SCI Life Member
"I am rejoiced at my fate. Do not be uneasy about me, for I am with my friends."
----- David Crockett in his last letter (to his children), January 9th, 1836
"I will never forsake Texas and her cause. I am her son." ----- Jose Antonio Navarro, from Mexican Prison in 1841
"for I have sworn upon the altar of god eternal hostility against every form of tyranny over the mind of man." Thomas Jefferson
Declaration of Arbroath April 6, 1320-“. . .It is not for glory, nor riches, nor honours that we are fighting, but for freedom - for that alone, which no honest man gives up but with life itself.”

03 November 2012, 02:49

ranb40

It should be possible. The 300 whisper made by SSK has the gas port about 6" down from the chamber. If yoiu install the gas port about 4" from the 223 chamber it should still have enough pressure to cycle the bolt carrier.

Ranb

03 November 2012, 07:26

jeffeosso

get an adjustable gas block ..

#dumptrump

opinions vary band of bubbas and STC hunting Club

Information on Ammoguide about
the416AR, 458AR, 470AR, 500AR
What is an AR round? Case Drawings 416-458-470AR and 500AR.
476AR,
http://www.weaponsmith.com

03 November 2012, 19:19

Rusty

Thanks, Jeffe!

16 February 2013, 04:24

J D

Any luck on subs, I just found a 223 barrel and I have a extra upper { I don"t like the way the brass deflector dents up my 300 blk brass} I have a match upper coming monday with no forward assist or deflector. I have enough parts to build a 223 upper. Thinking about setting it up for subs.

JD

23 February 2013, 07:11

J D

I got info to pass on, given to me by a guy who claims to have setup several ars to run subs. This is not first hand info, that I have proven but it sounds like good advice. It is how I had planed to try to make one work before speaking to this gentleman. Use at your own peril.

To run subs only open up gas port to same inside dia as gas tube. Use standard carbine spring and carbine buffer. That should get you close depending on powder and bullet weight combo. Trim up to 6 coils off spring as needed. Use the heaviest bullet your twist will work with.

To run supers and subs you need a dual port gas block. for super's the gas block port needs to match origional dia gas port before being opened up to the inside dia of gas tube. The sub port needs to match inside dia of gas tube.

You can use a adj.gas block but that requires retuneing every time you change ( at least I think so, I have not use one: therefore I am not sure).

JD