When buying an AR15 rifle, is there anything to consider? Well, yes there is. I must admit, when I bought mine, the main thing was how it looked, it is a awesome looking weapon and quite accurate. The gun is easy to take down, which means there is no excuse for not cleaning it after you use it. I knew that the bugs had been worked out after a rocky start. I also wanted a Colt, I had to have a Colt and with the day they would no longer be available to the public fast approaching I had to act fast and I did. I never thought about the length or twist of the barrel or what type of round I would be using, never had a clue and this is what I am going to talk about, amazing.

Barrel Twist

When the bullet exits the end of the barrel, it needs to be under control. A great analogy that is used to explain this and is used by many in their explanations, is to think of a quarterback throwing a football. He doesn’t just throw it per say, he uses his wrist to put a spin on the ball and that’s where the spiral effect, that I’m sure most of us are familiar with, comes in. This allows the ball to travel through the air with the least amount of resistance, it also allows the ball to travel further with greater accuracy. This is exactly the same for the bullet except, that in place of the wrist, the barrel has grooves on the inside. When the bullet travels through the barrel it is in contact with these grooves, which are in the form of a spiral and they cause the bullet to rotate just like the football, less resistance, more distance and more accuracy. My gun has a 1:7 twist, which means for every 7 inches that the bullet travels through the barrel, the bullet makes 1 revolution. If your barrel has a 1:14 twist the bullet will rotate 1 time for every 14 inches it travels through the barrel and there are several other barrel twists available. You can get 1:8, 1:9, 1:10, 1:12, well, you get the idea. They all have their uses and it just depends on your individual application.

The Bullet

Another aspect that people may not pay attention to is the bullet you are going to shoot. At first, I never thought about it. Just buy the cheapest box you can find and shoot away, right? Well, it turns out that the barrel you have on your gun, that is, the twist, should be considered when purchasing the cartridges. Knowing the twist of your barrel will give you an idea of what round to buy. The weight of the bullet, in grains, is of great importance. My AR15 fires the .223 cal. bullet. For this I will want to buy a heavier bullet. For instance I would want my rounds to be in the 69 to 90 grain range. This heavier bullet can handle the high rate of spin that my 1:7 twist produces. The RPM’s produced can go over 300,000, so the heavier bullet is the better choice. An interesting note about the 1:7 twist barrel is that it was designed to handle the longer and heavier tracer rounds used by the military. For barrels with twists of 1:9 or 1:10, considered to be a moderate twist, you would want something in the range of 45 to 69 grains. The 1:9 and 1:10 twist are better suited to handle this weight of bullet as the 1:7 and 1:8 twist is better suited to handle the heavier round. If you have a barrel with a twist rate of 1:12 or 1:14 you would want a lighter bullet in the 35 and 50 grain range. These rounds, called varmint rounds by many, are so light that if they were fired from an AR15 with a twist of 1:7 they could come apart in flight due to the extreme centrifugal force that they are subjected to. Interesting, isn’t it?

Closing

The next time you are buying ammunition, remember to look at the box and match it up with your particular barrel. This will insure consistent flight and accuracy of the bullet. If you buy different ammo all the time, your results at the range will be different and you’ll be wondering why you shot so well last week, but not so well this week.