How to Pick An AR-15 Barrel Profile

You've seen it advertised on so many upper receiver assemblies' barrels: "M4/Government profile," and "Heavy profile." What's it mean? What is a barrel profile, and why is it so important? Let's take a look.

What is a Barrel Profile?

The profile of an AR-15 barrel -- or any gun barrel, for that matter -- refers to its shape, weight, dimensions, and other characteristics, like fluting, tapers, and steps.

Why Barrel Profiles Matter

The profile of a barrel directly contributes to its accuracy and performance. The heavier the profile, the thicker the barrel, and the greater the accuracy. The more fluting and steps in its profile, the greater the barrel's surface area, and the better its resistance to heat. Tapered contours can promote greater stiffness and resistance to barrel harmonics, which promote greater accuracy, too.

Which AR-15 Barrel Profile is The Best?

Barrel profiles are too complex to universally apply a single, overall "best profile" to all firearms. But when it comes to the AR-15, there are just a few popular, proven profiles that tend to perform best in different roles.

Heavy Profile

"Heavy," or "HBAR," barrels provide the most accuracy and heat dissipation. As the name implies, these barrels are physically the heaviest of the lot. A 16" unit chambered in 5.56 or .223 often weighs well above 2 pounds, contributing more than 25% of the rifle's total weight.

Within this category, you'll find two sub-types: Contoured, and stepped. Contoured barrels tend to have even more mass than stepped barrels, promoting the greatest stiffness and accuracy. Stepped heavy barrels provide a slight weight reduction while affording high accuracy and heat dissipation.

This profile is best for those who want to maximize accuracy, and who engage in frequent rapid fire and magazine dumps, or outright full-auto fire. Heavy barrels are also typically found on ARs chambered in long-range calibers, like .308 Winchester, 6.5 Grendel, 6.5 Creedmoor, and other 6mm cartridges.

Shop long-range, heavy-barreled AR uppers here!

Mid-Weight Profile

Mid-weight barrels provide a great balance of high accuracy and maneuverability. With just slightly less mass than a heavy profile, they're still capable of maximizing the performance of any cartridge, while managing to shave a few ounces off your AR's total weight. 

Mid-weight profile barrels may also be advertised as having "straight" or "sporter" profiles. This profile is best for those who want to maximize semiautomatic accuracy without adding significant weight to their AR.

M4 / Government Profile

Arguably the most popular barrel profile for any AR-15, the M4/Government profile aims to reduce weight as much as possible, while maintaining an acceptable amount of mass to withstand heat from rapid fire. Accuracy is still acceptable in this profile, but the general theme of this profile favors light weight and maneuverability over benchrest accuracy.

This profile is best for those who want a lightweight barrel that's still capable of withstanding moderate to frequent rapid fire. When it comes to prebuilt upper receivers and off-the-shelf rifles, this remains the most popular barrel profile today.

Pencil / Lightweight Profile

Also called a "pencil barrel," the lightweight profile is as thin as possible, providing maximum weight reduction. The lightweight profile was used on the first M16A1s designed by Eugene Stoner. It was only after finding these barrels suffered degradation during full-auto fire that this configuration was ditched in favor of the heavier Government profile, which remains in use today.

Lightweight barrels do, indeed, have their place in the land of the AR-15. They provide significant weight savings, often weighing just over one pound -- a 50% or greater reduction in weight compared to a heavy or mid-weight barrel. Thanks to modern manufacturing, these barrels are far more capable of handling occasional rapid fire than they were over sixty years ago, while still affording high accuracy.