Results 1 to 1 of 1

Thread: 223 vs 5.56

  1. #1
    Apache's Avatar
    Join Date
    Dec 2006
    Central Louisiana

    223 vs 5.56

    Per Savage: Savage rifles chambered for the .223 Remington are designed exclusively for use with .223 Remington ammunition. Use of 5.56x45 NATO ammunition is not encouraged or endorsed, and use of said ammunition in ANY Savage firearm chambered in .223 Rem will void the warranty.

    With that being said some people just like/want to know the difference.

    A special thanks to bigedp51 for finding all this data.

    This is edited and condensed from some of his posts.

    Here is what I know from researching the subject.

    A short throated .223 has a throat length of .0250
    An AR15 has a throat length of .0500
    A Wylde chamber has a throat length of .0619
    A target chamber on a Savage has a throat length of .0566 (I believe this is what I have, see link below)


    Nothing is written in stone, I have fired M193 military 55 grain ammunition in my Stevens 200 BUT did so after checking the throat and the cases for signs of excess pressure. I have not tested the newer M855 military ammunition with it heavier bullet, so all bets are off on that ammo.

    Also in the past the military has waived chamber pressure limits on some production runs of military ammunition in order to meet velocity requirements. Meaning the chamber pressure can exceed standard military pressures for the 5.56.

    Below is a cartridge case being fired at normal chamber pressures, the red and yellow areas are the high stress points.

    Below is an exaggerated example of over pressure and cartridge case base expansion, you measure this with a set of vernier calipers or a micrometer. Also you will see brass start to flow into the ejector button on the bolt face and shows up as a circular ring on the base of the case. (easiest to see and the first sign of a pressure problem)

    Below is the best information I have found on the subject to date and is a good read.

    NOTE: Standard rated chamber pressure for the .223 is 52,000 cup or 55,000 psi in a short throated rifle, normally these rifles have a 1 in 14 to 1 in 12 twist. My Stevens 200 has a 1 in 9 twist and a longer throat, I have read that many of the newer .223 rifles have chambers big enough to fit a Company Lawyer in to prevent Court cases.

    5.56 vs .223 What You Know May Be Wrong

    As you can see below the military 5.65 throat is twice as long as a SAAMI "guideline dimension" .223 chamber throat.

    Savage makes .223 rifles in the following twist rates.

    1 in 14
    1 in 10
    1 in 9
    1 in 7

    My Stevens 200 with a 26 inch heavy barrel and a 1 in 9 twist has a throat longer than a AR15 rifle, BUT I bet the 1 in 14 twist Savage rifles are short throated.

    Meaning nothing is written in stone and your Savage might have a short throat which will cause high pressure when military 5.56 ammunition is fired.

    Gauges are made for checking your throat length below.

    Posting on subject below

    Is it .223 or 5.56? Chamber gage now avail.

    Standard SAAMI .223 throat and military 5.56 throat below, the SAAMI chamber diagrams are "guideline dimension" and can be changed by the firearms manufacture. A long throated Weatherby rifle is an example.

    Last edited by thomae; 01-07-2014 at 09:57 PM. Reason: Trying to find picture links that were broken
    Prefit Rifle Barrels


Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts