New urban legend about twist rates.

Aparently, there’s a new urban legend about barrel twist rates making its way around. The latest Gun Counter Genius truisim goes like this:

“It isn’t the twist rate that matters, it’s the barrel length. As long as the barrel is long enough to spin the bullet two complete reveloutions, all bullets will be stable.”

There are so many things wrong with this statement that it’s best just to say it’s totally and completely WRONG and leave it at that. Obviously, someone has invented armchair logic that says that a bullet that only spins part of a revolution will be “unstable”, therefore this “two revolution” concept.

The falseness of this statement can easily be seen in handguns, which almost never the combination of barrel length and twist rate such that they can spin a bullet 2 times in the short length of a barrel. Many rifles are like this as well, any 1:12 twist rifle would have to have at least a 24 inch barrel if this theory were correct.

I have now heard this falsehood repeated twice in the last month. Once at Cabelas (NOT by an employee, thankfully), and once on an internet forum. I had never heard this little ditty before, so obviously it’s spreading like wildfire.

This latest urban legend follows a long line of fine shooting and firearms-related BS. For example, the infamous “.223 and 5.56 are different” whopper, I’m sure, is high on everyone’s all-time favorites list.

Don’t be taken with this latest one.

Grouse

HAHA! Haven’t heard that one yet.

Are you saying the .223 is the same as the 5.56 Nato? Did I understand that statement right?

The .223 and Nato 5.56 cartridge are different. The 5.56 has a longer case length in the throat area, and run higher pressures. Hence 5.56 can shoot .223 but not the other way around.

Now you can take a 5.56 case and length resize and load to .223 specs to fit non 5.56 .223 rifles.

Quote:

---

Are you saying the .223 is the same as the 5.56 Nato? Did I understand that statement right?

The .223 and Nato 5.56 cartridge are different. The 5.56 has a longer case length in the throat area, and run higher pressures. Hence 5.56 can shoot .223 but not the other way around.

Now you can take a 5.56 case and length resize and load to .223 specs to fit non 5.56 .223 rifles.

---

This has been exhaustively debated all over the internet.

The .223 and 5.56 cartridges are interchangeable. You can fire a .223 in a 5.56. And you can also fire a 5.56 in a .223 chamber.

You are correct, the actual dimensional characteristics of the rounds are slightly different. This has nothing to do with making the 2 rounds “incompatable”, it was done for a variety of reasons related to making millitary rifles function and cycle better.

If it were true that resizing was needed to turn the .223 case into a round capeable of being fired by a 5.56, then seperate reloading dies would be required for both calibers.

The generalization that the 5.56 is loaded to a “higher pressure” and related generalizations about the cases’ ability to withstand pressure, etc, etc, are all generalizations and are not true across the board. The specific pressure of any loading is down to that particular loading and no blanket statement can be made about the 5.56 or so called “millitary spec” ammo being “higher pressure”. Chamber pressures also depend on the loading AND the characteristics of a specific rifle. Brass thickness varies wildely between makes.

There was a time very early in the 5.56 rounds development that Colt made a series of rifles with a significantly different chamber spec than the current and final 5.56 spec. Much has been made of this, but very few of these rifles were made and there is no sign that they were broadly available to the civilain market, so very few probably actually survive today.

I’m sure there is no hope of the 223 vs 556 debate ever dying, but I’m hoping this new one about twist rate lives a short life and goes away. The last thing we need are a bunch of hunters believing that the only “accurate” rifle has a fast twist and a long barrel.

Grouse

Grouse

You have to be careful with your statements

Faster twist
Long barrels

Because a faster twist stabilizes a heavier bullet…a good thing…more energy, less windage issues and a longer effective useable range.

A longer barrel allows for a better burn/usable pressure range thus giving the shooter the ability to use the above application to its full potential.

A good example will be my 38” 9 twist barrel using H50BMG and pushing a 414 grain 375 cal. bullet which will run 3250 fps without any pressure issues.

With a stepped down BC grid, I still will only have to dial around

44.4 mils at 3520..dial and hold hash marks
10.2 mils at 1760..dial
4.3 mils at 1000..dial
That being zeroed at 100

Stuck in a snow storm, hopefully not to technical here

Cheers

A good read after actual pressure testing he feels you can feed 5.56 in .223 chamber rifles as long as it is not a steady diet.

web page