5.56 vs .223

[paintman]

i have an ar 15 that is chambered for 5.56. but ive heard alot of people say if a gun is chambered 223 you cant shoot 556 from it. i know there is a gas pressure differance but what are the real affects of shooting 556 from a 223? always wondered but never really knew for sure.

 

[sgreen3]

Here is some post already covering the topic

https://www.indianagunowners.com/forums/ammunition_and_reloading/137854-223_vs_5_56_a.html

https://www.indianagunowners.com/forums/ammunition_and_reloading/136682-223_v_5_56_a.html

https://www.indianagunowners.com/forums/ammunition_and_reloading/108025-223_vs_5_56_a.html

https://www.indianagunowners.com/forums/ammunition_and_reloading/15449-223_vs_5_56_a.html

 

[paintman]

wow thanks. guess this has been talked about a few times before me. i guess my other question would be is it going to put strain on my gun faster using 556 over 223?

 

[sgreen3]

Yup a couple And no you'll be fine, the rifle is chambered for 5.56 so it will eat which ever you want. i only use .223 becasue its easier to find in stores were Im at. But I re-load now so I only .223.

 

[paintman]

perfect. you answered all my questions! thanks for the help

 

[sloughfoot]

55 grain fmj M193 5.56 Mil-Spec from the mid-sixties to now is identical in pressure to commercial 55 grain fmj 223.

The deal breaker is the 5.56 NATO which is the 62 grain green tip penetrator and sister cartridges. This cartridge was adopted in 1988 or so.

This NATO spec round is loaded to much higher pressures and should not be fired with a 223 chamber that does not have a modified leade to accomodate it.

 

[paintman]

seems like basically the same things you have to watch out for on the m1 garand. as far as comercial ammo and older m2 ball gas pressures. i kinda figured i was on track of being right but a few people i work with were asking me and i really wasnt 100% sure. didnt want to give any bad info.

 

[brian_a_mcmillen]

We are talking about reloading right? If you're using a proper book, they will list the chamber pressures and velocity of each charge/bullet combination as well as overall length and other dimentions. The Lyman book combines the .223 and 5.56 together along with all the different projectile combinations. Depending on reloading experience, start with a lesser charge and work your way up. You can tell when the pressure starts getting up there by flattened or even missing primers after the round is fired. As far as AR-15's go, most are 5.56 anyway.

 

[teddy12b]

You have the 5.56 barrel, so you really don't need to worry about it.

Like it was mentioned earlier, you don't want to shoot 5.56 in a 223. I have a 223 bolt action rifle that I'd love to shoot the 62gr M855 round in it, but it's got too much pressure. My way around that is to buy just the actual bullets themselves and load them in 223 brass at 223 pressures. The problem of using too much pressure to fire a particular bullet is then solved.

 

[Leo]

Unless it is some odd ball rifle that I have never seen, your bolt action is far stronger than any AR based rifle. Most of the bolt action .223 have the same surface area on the bolt action lugs as a .308. A 62,000 psi .308 bolt action rifle deals with peaks of 11,700 pounds of rearward thrust all day long with no problems. A 62,000 psi load on a .223 cartridge head can only generate about 7500 peak pounds of rearward thrust. No worries on the strength of the action.