AR-15 Quad Rails: Best Practices for Upgrading

AR-15 Quad Rails: Best Practices for Upgrading

One of the biggest reasons AR-15s are so popular is their customizability. And one of the most popular components to upgrade? The handguards.

You see, AR-15s usually come with basic plastic two-piece handguards. Replacing these handguards with a quad rail lets you mount accessories such as lasers, bipods and flashlights.

So what are things to think about when it comes to these quad rail upgrades? Let’s go over a few best practices.

Two-Piece vs. Free-Float

Two-piece rails are the easiest to install. You simply:

  1. Remove the plastic handguards by pushing the delta ring towards the receiver.
  2. Lift off the pieces.

Sounds easy, but the spring behind the delta ring is strong. You need three hands, a friend or a handguard-removal tool such as Promag’s AR-15 and M16 forearm removal tool.

The new rails are a direct replacement for the plastic handguards.

Free-float rail systems require more work. They are usually one complete piece that mounts to a replacement barrel nut. No part of the rail touches the barrel. This helps with cooling and accuracy.

You will usually need to remove the flash suppressor, front-sight post or gas block, gas tube, delta-ring assembly and barrel nut.

This would be a great time to replace any part of your upper assembly like the barrel, flash suppressor, gas block and front sight since you would be removing everything.

Tools required to install a free-float system include:

If you acquire all of the tools necessary to install a free-float rail system, you also have all of the tools necessary to build your own upper from scratch.

Be prepared to have all of your shooting buddies bring you their rifles to install their rail systems. It is easy to do with the proper tools.

Geissele AR-15 Quad Rails Free Float
This Geissele free-float rail is a high-quality addition to your AR-15.

What Size Handguard Do I Need?

For the most part, AR-15 uppers have three different sizes:

  • Carbine
  • Mid-length
  • Rifle length

For the handguards:

  • Carbine lengths are 16” or less
  • Mid-length are usually found on 16” to 18” barreled uppers and use a mid-length gas system
  • Rifle length handguards fit on a 20” barrel

For the rails:

  • Carbines take 6-3/4″ rails
  • Mid-length take 8-1/2″ rails
  • Rifle-length rails are 12” long

Exceptions are Colt carbines, which are 6-7/8” long. Either way, when it comes to AR-15 quad rails and handguards, size matters.

Leapers AR-15 Light
Adding a handguard with rails allows you to attach tons of lights, laser and other accessories to your AR-15.

Covers vs. Ladders

Once the rails are installed, they look great, although are not exactly comfortable to grip. The sharp edges of the rail can cut or rub your hand the wrong way.

Because of this, many AR-15 owners use rail covers or ladders to protect the rails and their hands when shooting.

  • Covers completely cover the rails and offer the most protection.
  • Ladders fill in the portion between the rails, providing some comfort and protection, but are not quite as bulky as covers.
AR-15 Rail Covers
These rail covers will help make your quad rails more comfortable to grip while firing.

Have any tips for upgrading AR-15s with quad rails? Let us know in the comments section below!

Editor’s note: This post was originally published in December of 2010. It has been completely revamped and updated for accuracy and clarity.


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