Is .223 Remington, 5.56x45mm, M193, M855, etc. all just a marketing gimmick now?
On Saturday I took out one of my 16" AR Carbine and a 20" AR Rifle and choreographed a bunch of 55gr ammo.  They were .couple of Federal and Winchester brand .223 Remington hunting ammo, some new Federal M193,new Federal 5.56, older XM193, old yellow box UMC .223, etc...all were 55gr.  I was expecting those ammo that were marked 5.56 and M193 to have some increase in velocity compared to .223 Remington marked ammo.  What I found is that .223 hunting ammo gave some of the highest velocity while newly purchased Federal M193 gave the second lowest velocity (yellow box UMC had lowest velocity).  I would have thought since 5.56/M193 were loaded to higher pressure than.223 that they would give higher velocity but it didn't turn out that way.  Does that mean .223 Remington, 5.56x45mm, M193, M855, etc. all just a marketing gimmick now?

How about some actual velocity numbers?

All depends on the  product. I can tell you that GECO .223 is indeed slower out of 3 barrel lengths, than Geco 5.56, among other products, like .223 Remington American Eagle, vs 5.56 AE

So um. Data?

5.56 is more about crimped/sealed necks, crimped/sealed pockets and pressure. Not necessarily velocity.

When did 5.56 and .223 actually diverge? From the time I started shooting in the '80's and '90's, all ammo was .223/556. and I always read that it was interchangeable, kinda like 9X19 vs. 9 Luger. Then, starting in the mid 2000's, when I started reading on the interwebz, that chambers were different and shooting 556 in a 223 will cause detonation, death, and birth defects...(or at least popped primers)

I certainly believe and understand that there are differences between 5.56X45 and .223, I cannot believe I shot the round for 20 years without hearing about it.

I have not purchased any 223Rem ammo that was not crimped and sealed just like 5.56

 

I do not have the 5.56 test up yet.


.223 Load:



5.56 Load:

In general, the 5.56 vs 223 is more pressure now than just about anything else. The newer powders and components have closed the gap between the two.
I would be interesting to see some actual numbers though. Seems ~ 200 FPS was the going rate between the two. I'm convinced it is closer now, but have no numbers to prove it of my own.

Um, 5.56 specifications do include velocity, in general. Defined in some MIL-STD or other, IIRC.

I spent a couple hours testing loads last week.

.223 Federal AE
Avg 2900

.223 Hornady SP
Avg 2840

XM193
Avg 3136

16" bbl

When you consider FMJ needs 200fps to fragment that 236 extra FPS translates to significantly longer effective range.

This isn't GD - Eric802