AR Ammo, Barrel Twist, and Gas System etc.

AR Ammo
1) M193 Standard military cartridge 55 Grain Lead core boat tailed copper jacket bullet.

2) M196 Tracer Possible corrosive to gun barrel they come in orange or green tipped and should be used in a 1 tracer to 4--  M193 regular bullets. Used for signaling or for laying down accurate night fire or incendiary ignition.

3) M856 Tracer  same use and characteristics as above except the projectile is near 64 grains and has a longer burnout time.

4) M188 Dummy used for gun handling training. The shell has a series of about six long dents uniformly down the body of the shell.  

5) M200 Blank this is used with a muzzle clip on generally read in color which allows the flash powder to cycle the gun to keep from manual operation. This is for simulated fire with no projectile.

6) M855 Green tipped steal penetrator 62 grains. This bullet is good out to 90 meters and is not as susceptible to deflection from glass, thin metal, or small twigs and leave. Its sole purpose was to penetrate solders thin metal helmets. It was produced in abundance cheaply for a military market and filtered into the civilian market so its low price was very popular to sportsmen for hog hunting. Currently banned by Obama.

7) M862 SRTA  Short Ranged Training Ammo only efficient target ammo out to 25 meters for quick fire training,  silhouette short range target shooting. It is also used in indoor training where range use would preclude regular service ammo because of close quarters training dangers.

         

AR Barrel Twist Rates

A) 1 in 7 twist long rang Match ammo from 77to 90 Grains is what is suggested for long range sporting use but the military ammo seen above has a 62 M855 and so most military guns have a 1 in 7 twist but also fire the 55 grain bullet as well. The M855 performance out to 300 yards in the AR type guns with a 1 in 7 twist is good. This was probably why Obama banned this bullet. It makes one suspect that our political conglomerate may have other ideas besides the public good when it comes to disarmament.

B) 1 in 8 twist Medium to long range bullets  62 – 77 grains but Stabilizes many of the heavier bullets  as well for long range use. 55 grain bullets preform extremely well well at close range but as the range increases accuracy falls off.  

C) 1 in 9  twist this is for bullets from 40 to 62 grains but the gun can also shoot heavier bullets but accuracy diminishes somewhat for the heavier bullets.

D) 1 in 12 twist work best with light bullets at higher velocities for long range use for varmints

AR Gas System
Gas flow determines recoil- to much barrel after the gas tube can increase gas pressure and recoil and can cause excessive gun deterioration and ware. To short of a barrel after the gas tube can cause functioning problems such as insufficient cycling glitches causing jams. Military AR guns are set up for a faster cycle rate still allowing for recovery after recoil so you can aim and make your next shot. For civilian barrel purchases of different AR barrels gas function is usually thought about by the barrel manufactures to a great degree so what you buy will work. Some have experienced problems but in a pinch an adjustable gas block will let you tailor the gasses so you have the lightest recoil and the gun still functions but you sacrifice cycle rate.Though there are exceptions for the most part worrying about this gas system stuff is not necessary and the barrel you buy and the matching gas system is not a problem.

Muzzle Brakes verses Flash Hiders

Muzzle brakes are a good addition to a gun. What happens is that when the gun is fired the muzzle climes up on recoil. A good muzzle brake uses the spent gasses as the bullet leaves the barrel to physically hold the muzzle down allowing for quicker response for the next shot, and also allows you to cray a lighter gun barrel. in other words you can approximate more accurate shots of a heavy barrel gun and not have to carry the extra weight.Do your research before buying your muzzle brake,  some are no more than glorified thread protectors which do nothing but they look good and cost a pretty piney.

 Flash hiders are illegal but what they do is to allow the unburned powder from the cartridge to burn in a controlled situation lessoning the flash.  
Richard W. Norman   Author of American Handbook on Guns Ammo and Freedom