Why was 223/5.56 annointed?
- Thread starter kcub
- Start date
this isnt the answer you are looking for but...after having worked in government consulting for years I would guess someone was going to make a lot of money off of the decision and person/committee that made the decision was connected to that person/company. I am sure they have some official stated reason about caliber etc but every decision I see from the top is made because it benefits friends, former college buddies, etc.
Short story: the military wanted a high-velocity, smallbore cartridge. Armalite and Remington came out ahead in the race. It's actually a long and convoluted story. Daniel Watters has a detailed history here.
dieselbeef
New member
id like to know why the calibers are so close together. the 223 and the 556..why have 2 cartridges that fire from the same rifle as they do
big al hunter
New member
.
They are exactly the same cartridge. Different names because the commercial market in the U.S. likes inches more than millimeters. The military uses metric because we are allies with NATO. Almost all of NATO uses metric as a standard. Another example of this is the 308 Winchester, also known as 7.62 X 51.
As far as the different loads....many cartridges have different levels of loads on the market. There are several levels of 45-70 for different action types. 45 Colt is loaded for old revolvers and more powerful loads for modern revolvers.
dieselbeef
New member
i waited for that...why spec the 2 so close
big al hunter
New member
The case dimensions are the same except a slight radius at the shoulder to neck transition. I attached the spec's for reference. The difference in chambers is in the additional leade to the lands, not the cartridge dimensions. If they were different enough to matter we would not use them interchangeably and this type of discussion would not occur.
There are many articles that argue to one side or the other on pressure differences. Most of which is because the two cartridge designations use different pressure measurement systems that do not directly correlate. One is psi or pounds per square inch. The other is cup or copper units of pressure. When you compare the two directly it appears that the 5.56 has far more pressure than the 223. Actual pressures depend on actual conditions inside the firearm used. Some testing done independently shows the actual pressures are very similar in some test guns and very different in others.
We could argue this all day, because we each have a different way of looking at it.
There are many articles that argue to one side or the other on pressure differences. Most of which is because the two cartridge designations use different pressure measurement systems that do not directly correlate. One is psi or pounds per square inch. The other is cup or copper units of pressure. When you compare the two directly it appears that the 5.56 has far more pressure than the 223. Actual pressures depend on actual conditions inside the firearm used. Some testing done independently shows the actual pressures are very similar in some test guns and very different in others.
We could argue this all day, because we each have a different way of looking at it.
Attachments
"...the military wanted a high-velocity, smallbore cartridge..." No, they didn't. Nobody wanted either the M-16 or the .223/5.56(same thing before there was an internet. Common myth is that they are not exactly the same.).
A M-16/AR-15 was never intended to be a main battle rifle. It was designed to be an air crew survival weapon, period.
The U.S. military was ordered to adopt 'em by Robert McNamara because he thought he(being a FORD executive) knew more about what was required than the military leaders.
Then the rest of NATO was told adopt it or the U.S. would pull out of NATO. Just like they were when the 7.62 was adopted ten years earlier.
A M-16/AR-15 was never intended to be a main battle rifle. It was designed to be an air crew survival weapon, period.
The U.S. military was ordered to adopt 'em by Robert McNamara because he thought he(being a FORD executive) knew more about what was required than the military leaders.
Then the rest of NATO was told adopt it or the U.S. would pull out of NATO. Just like they were when the 7.62 was adopted ten years earlier.
In a nutshell, the story as I know it, goes,
Back in the day, the Air Force got its small arms and support (spare parts,etc.) from the Army. The Army was doing away with the M1 Carbine, which the Air Force used.
Gen Lemay needed to find a replacement to arm the SPs guarding his airbases.
He was introduced to Stoner at a party, and got to check out Stoner's AR design. (I believe in .222Rem). He thought it was handy and dandy for his airbase security people.
When the "whiz kids" at the MacNamara defense dept got wind of it, they decided it would be the best choice for everyone.
The Army, getting its orders, selected a set of performance criteria which the .222 simply could not meet. The 5.56mm was developed to meet those specs. .223 Rem was the name for the round when sold on the commercial market.
Back in the day, the Air Force got its small arms and support (spare parts,etc.) from the Army. The Army was doing away with the M1 Carbine, which the Air Force used.
Gen Lemay needed to find a replacement to arm the SPs guarding his airbases.
He was introduced to Stoner at a party, and got to check out Stoner's AR design. (I believe in .222Rem). He thought it was handy and dandy for his airbase security people.
When the "whiz kids" at the MacNamara defense dept got wind of it, they decided it would be the best choice for everyone.
The Army, getting its orders, selected a set of performance criteria which the .222 simply could not meet. The 5.56mm was developed to meet those specs. .223 Rem was the name for the round when sold on the commercial market.
big al hunter
New member
Common misunderstanding. NATO spec is P.S.I. SAAMI spec is C.U.P. The spec for 223 is 52,000 C.U.P. and 62,000 P.S.I. the same as 5.56 P.S.I. spec. Just a different measurement scale used for standard.
Learned something new today. I thought I had researched it enough to to think I found the correct answer. I wish I could remember the long article ( from a respected source iirc )I read that kept referring to the pressure differences.
223 and 5.56 are essentially the same. The military chooses to cut chambers to slightly different specs and 5.56 CAN be loaded to slightly higher pressures. Even though they use different measuring methods 5.56 CAN be loaded slightly hotter. Think of it as 223+P, but just because specs say it CAN be loaded a little hotter that doesn't mean all of it is.
Rounds marked as 223 can be fired in 5.56 chambers with no concern. It is theoretically possible to run into problems shooting 5.56 in 223 chambers, but the 2 have been used interchangeably for years. No one knew there was supposed to be a difference before the internet and I've never heard of a problem.
I compare the difference to 30-06. Over the years that round has evolved and you are actually more likely to run into problems with certain 30-06 loads and chambers that are not compatible than with 223 and 5.56. If you compare pre WW-1 era 30-06 loads, to WW-1 era loads, and WW-2 era loads alongside modern hunting loads you could easily justify 4 different names for that round too. Actually we do have two, 30-03 ammo can be fired in 30-06 chambers, but not the other way. Try shooting modern hunting 30-06 loads in a WW-2 Garand, and you'll have problems. But it is labeled 30-06 and chambers in the rifle.
Rounds marked as 223 can be fired in 5.56 chambers with no concern. It is theoretically possible to run into problems shooting 5.56 in 223 chambers, but the 2 have been used interchangeably for years. No one knew there was supposed to be a difference before the internet and I've never heard of a problem.
I compare the difference to 30-06. Over the years that round has evolved and you are actually more likely to run into problems with certain 30-06 loads and chambers that are not compatible than with 223 and 5.56. If you compare pre WW-1 era 30-06 loads, to WW-1 era loads, and WW-2 era loads alongside modern hunting loads you could easily justify 4 different names for that round too. Actually we do have two, 30-03 ammo can be fired in 30-06 chambers, but not the other way. Try shooting modern hunting 30-06 loads in a WW-2 Garand, and you'll have problems. But it is labeled 30-06 and chambers in the rifle.
DPI7800
This is a common myth that won't go away. Lake City 5.56 brass actually has more case capacity than pretty much any commercial .223 case.
Now, this does apply to military 7.62X51 and 30-06 brass. They are thicker, and do have less case capacity than most commercial .308 and 30-06 brass.
This is a common myth that won't go away. Lake City 5.56 brass actually has more case capacity than pretty much any commercial .223 case.
Now, this does apply to military 7.62X51 and 30-06 brass. They are thicker, and do have less case capacity than most commercial .308 and 30-06 brass.