Why 556

The 5. Military to use in the M rifle. Indeed, the MA1, MA2, and M-4 rifles and carbines commonly used by the US Army and Marine Corps as well as the other branches of the military over the past few decades are all chambered in 5.

However, the MA1 has a slower rifling twist rate than the other two since it was designed to use different bullet weights. Due to the military roots of the cartridge, the 5. Since, all other things being equal, a shorter leade results in higher chamber pressure when compared to a longer leade, this means that firing 5.

Indeed, not only is it safe to shoot in a chamber and 5. Can you shoot in a 5. Can you shoot 5. Do not shoot 5. If you fire 5. More likely, the excess pressure levels will damage the rifle itself or blow the primer out of the primer pocket into the internal workings of the rifle. So, if you observe any signs of excess pressure like blown, cratered, or flattened primers , stop shooting that ammunition in your rifle immediately.

First, find out if your rifle or handgun is a. On AR rifles or carbines, look on the top of the barrel near the muzzle. These two bullets have raised controversy in many areas. Some shooters claim the bullets are interchangeable while another group disputes these claims. The truth is that although they are almost similar, slight differences in the make of the allow it to perform differently from the 5. It is important that you note the 5. The 5. The casing on the has Remington inscribed on the base.

The military grade 5. The longer throat allows more holding capacity for gun powder in the 5. The bullet has dimensions that seal the contents tighter as compared to the 5. This compensates for the pressure difference in the two when fired from the same case.

The smaller gun powder capacity on the bullet, however, means that the have lower power as compared to the 5. External Ballistic tests on the using a standard 55gr bullet leaving the barrel at 3,fps reveals that the fps slows down by less than half of the velocity at a yard distance. The energy loss at this point is about pounds.

The bullet also drops about 64 inches due to gravitational pull. All this happens in. These ballistics stats mean that the is accurate and has less jump. The accuracy is enhanced by the shorter lead when the bullet moves from the case to the barrel.

Although they are of the same size, the two bullets have different results when shot from a rifle. Note that the 5. The packs more pressure and gun powder, meaning that it travels faster and is more accurate. Although the can be shot from the 5. The is also a little heavier, which means that the effect of the atmosphere on its trajectory is less than it is on the trajectory. This means the 5. The Remington bullet is lighter and has less pressure in its chamber. Comparing the stopping power of the two bullets when fired from a 5.

In simpler terms, the stopping power means that the 5. There was no dangerous spike in pressure from firing 5. While pressures were elevated in comparison to one of the 5. This unexpected difference was also borne out by chronograph measurements, which showed that the Weatherby Vanguard Compact bolt action rifle fired the XM ammunition all of which was from the same lot at a velocity which was higher than the lower pressure 5.

In fact, the higher pressure 5. As my gunsmith friend has told me several times, velocity is a sign of pressure, and this second 5. I have owned approximately sixty AR barrels, with a fairly even distribution of. I have also owned numerous bolt action rifles chambered in. I have fired. Although my results are still anecdotal, I do not recall seeing anything worse than popped primers from firing 5. Popped primers are definitely a sign of excess pressure or an abnormal pressure curve, and should not be ignored.

They can become wedged in some of the more important bits of an automatic rifle, causing it to stop functioning, and while this could be annoying at the range, it could also be fatal in a self-defense situation. Summary: Velocities and pressures for 5. My greatest concern while researching, experimenting for, and writing this article was whether or not I was putting out accurate information.

In order to double check my results, I consulted with over half a dozen industry professionals, all of whom have far more experience in this area than I do. They work for highly respected laboratories, companies, and organizations. While I do not wish to put words in their mouths, none expressed great concern that I would have a rifle blow up in my face during the course of my experiments.

That said, one noted gunsmith told me about a test he had heard of, conducted by an ammo manufacturer, in which 5. Their results were slightly different from ours, which can be expected due to the different barrels and the different testing methods, as well as different lots of ammunition, but overall the results were quite similar.

Note that the. Encountering an undersized chamber in the real world is likely, especially if it was manufactured cheaply and with little quality control procedures. I now spend just a little more money on my guns and equipment, and get a lot more quality. If you would like to check your 5. The first difference is the higher pressure level of the 5. A Remington is loaded to approximately 55, psi. The second and most important difference between the two is the fact that a 5.

This allows approximately one more grain of powder to be loaded into a 5.