.223 vs 5.56x45

[CAJUNLAWYER]

Is it safe to shoot 5.56x45 out of a bolt action .223 ?

 

[johngalt]

Officially, no. There are a couple issues:

5.56 can be loaded to higher pressure than .223.

5.56 chambers have a longer throat than .223. I think this means that 5.56 can use longer, heavier bullets. Using bullets that are too long in a .223 chamber means that the bullet may contact the rifling, which can dramatically raise chamber pressure.

However, I've used 5.56 (55 gr bullets) in my Winchester M70 with no problems.

 

[Harrison]

It depends. 5.56 brass is loaded to significently more pressure (NATO pressures are higher than SAMMI) than a .223, that is part of the reason for the long throat (Wheatherby used the same principle to reduce pressure). Some .223 throats are longer or shorter than others, so it kind of depends on the throat in your particular rifle. If you have a good solid bolt action, you are unlikely to have a Kaboom, even with a short throat. Go ahead a try a few rounds. If your bolt is sticky and hard to open, then you know to stay away from 5.56

 

[armadillo]

I'm no expert, but it seems to me that you should be OK if you stick to the 55 gr. 5.56 loading.

As a practical matter, I shoot both 223 and 5.56 in an AR and only 223 and reloads in the 223 Rem.

 

[Rule3]

Most AR's are 5.56 so the 223 is OK in them. the reverse is not "officially" OK.

5.56 are really not supposed to be shot in a 223.