Why is the 5.56 half the price of .223? Is it the FMJ that makes it so much cheaper?

Yep that and be aware that some has steel cases and also polymer cases.

So in a bolt action 5.56, should I just use the .223 or are there certain brands of 5.56 that are ok?


Sorry, new gun to me and trying to learn the difference. I know you can use a .223 in a 5.56 and you can't do it the opposite way but I cant find any other info about the differences (casing, tips & such)

Thanks

The main difference is the pressure in which the 5.56 operates at. Its higher than that of the 223. Main reason the 5.56 is cheaper with all things being equal is that the 5.56 is super mass produced.

Talk about a can of worms the old 223 vs 5.56 is about as wormy as it gets.
They are the same pressure wise and dimensionally although the NATO pressure specs are measured different. There is a difference in the specs on the actual chambering(reamer spec)with a slight change of the leade.
Since no one ever wins this debate and the Wive's tale continues thanks to lawyers from the manufacturers I will just say this.

First find me anywhere anyone who has ever had an actual problem shooting 5.56 in a .223...google it whatever I have not heard of one instance and I know literally thousands and thousands of rounds of 5.56 are fired thru .223's every year by folks who have no idea which chambering they even have.

Next I would use Hornady's Superformance ammo as an example. A 53gr Bullet running 3500fps( I have chrono'd it several times) is hard to duplicate unless you run max loads...hotter than most manuals say 5.56 is supposed to be loaded.
It would only be a guess of course but I bet it is loaded to higher pressures than most 5.56 is.

Good read on the differences: http://www.luckygunner.com/labs/5-56-vs-223/

As for the cost, 5.56 is a military round and often fmj. So it's produced in bulk for military contracts and also sold to the public. .223 is a SAAMI standardized round and not made in large quantities like 5.56 is.

Ammo for the 5.56 NATO originally was limited to the same pressures as SAAMI .223 Remington, but there was an allowed increase of about 3000 psi back in 1999 and I believe is was applicable to M855. Beware of loading data that gives the green light to 62000 psi.



Here is how it was to be done in 1984.

I have a copy of a 1999 document which indicates the pressure limit was upped to 58700 psi average, but I cannot find a link to it.

M855A1 is said to be loaded hotter but I have found no specification documents on it and it may be that it is still classified. In addition to all the positive hoopla that I have read about the A1 round, it has also been said that the military is experiencing longevity problems with rifles firing the M855A1 round. I have not looked into the question for about eight months so there may be newer info out there.

Regardless, I am sure that many of us are loading what we intend to be .223 Remington ammo beyond the 55000 psi spec. We have no way of knowing. If the intent is to load to 5.56 NATO spec, it would be foolish, IMO, to strive for 62000 psi. That 62000 number is lifted out of a European spec for 5.56 NATO ammunition that is developed and tested using an entirely different measurement method.

Thanks fellas, so I'll just buy a few boxes of each and see which one shoots the best.