Extended Drop-In Quad Rails: Installation and Setup

Are you looking for a way to modernize your AR-15’s drop-in handguard? An extended quad rail may be the right solution for you. In the past, there was no way to extend the handguard beyond the front sight. That all changed with the advent of the drop-in handguard system.

A drop-in handguard is one solution to having a longer rail on your AR-15 without costly upgrades. Most modern AR-15 platforms utilize a free-floating rail, which eliminates barrel flex. And if you own a rifle with a drop-in handguard, converting it to a free-float system may not be an option.

Converting your rifle to a free-float system would require multiple new parts and a gunsmith fee unless you have a bit of gunsmithing knowledge and experience yourself. For those who are not aware, the difference between a drop-in handguard and a free-float handguard is how it attaches to the gun. A free-float handguard only attaches to the upper receiver and does not touch the barrel, while a drop-in handguard is wedged in between the upper receiver and the A-frame of the front sight. Pressure from the delta ring keeps the handguard in place.

But what if you need something longer than a short handguard in between your front post and receiver? This is where the extended drop-in handguard comes into play. This type of handguard is not exactly tool-free and as fast as a traditional drop-in handguard, but it’s a simple process to complete.

What is an extended drop-in quad rail?

As the name implies, an extended drop-in quad rail is a handguard with Picatinny rails on all four sides. It also extends past the front sight, giving you more room for attaching accessories to your rifle. Drop-in handguards come in two main pieces: a top and a bottom. An extended drop-in handguard will have a notch on the top portion of the handguard that fits over the front sight. The bottom is in two pieces to allow room for the sling swivel, which is underneath the front sight.

Even though the handguard is longer than the front post, it has a molded area underneath that fits in between the front post and delta ring just like the original one. The only difference is the third smaller portion of the bottom handguard must attach with screws. There are also places for screws to secure the upper and lower portions of the handguard together across the entire length of the handguard for added stability.

This is a perfect way to place an extended rail system on a rifle with a fixed sight and shorter handguard. I had an older Bushmaster XM-15 that I wanted to upgrade, so I installed an extended quad rail to it. Let’s go over the process of removing your current handguard and installing an extended quad-rail handguard in its place.

Removing the Old Handguard

Even if your gunsmithing abilities are at zero, switching to a drop-in handguard is not all that complicated. Removing the old one is probably the hardest part about it. The delta ring is putting pressure on the handguard by pushing it against the front sight. To remove it, you must pull back on the delta ring (see photo below) while pulling down on the bottom portion of the rail. Repeat the same process with the top, and the uninstall will be complete.

Depending on your rifle, the delta ring may have a lot of pressure on it, and some are easier to remove than others. I like to place the butt of the rifle on my workbench with the barrel facing up. I grip the delta ring with both hands and pull down on one side while using my thumb to push out on the handguard. If you are still having trouble, find another person to pull the handguard off while you pull back on the delta ring.

Be mindful that your rifle’s gas tube runs directly under the top of the handguard. Removing the handguard won’t hurt the gas tube, but you don’t want to bend it when pulling the upper portion of the handguard off. I would also take this opportunity to inspect and clean this part of your rifle. A lot of dirt and build-up may be on the barrel if you have never removed it and cleaned it before.

Installing the Extended Drop-In Quad Rail Handguard

Start with the top portion of the new handguard and set it over the front sight. There should be a section on the inside of the handguard that fits in between the delta ring and the front sight post (see photo below). Align the section on the front post first and then pull back on the delta ring and let the handguard “drop” in. You can also try putting the handguard under the delta ring and push down until the top portion falls in place.

Next, align the larger of the two bottom sections the same way. One end will fit under the front post and the other under the delta ring. The sling swivel will fall between the two lower portions of the handguard. Hold the handguard in place and install the screws from the top side of the handguard to hold it together. The number of screws holding the top and bottom together may depend on the brand of handguard you are using.

Summary

That’s all there is to it. Now, you will have an extended handguard with four Picatinny rails, offering ample attachment space for tactical lights, lasers, backup sights, and other accessories. You can buy quad rails that replace the original handguard if you do not want an extended one. But that little bit of extra room is nice to have. Especially if you want a foregrip further down on the barrel or some other type of accessory. I prefer a smooth M-LOK-compatible handguard, but a quadrail brings back that older style of handguard.

This made a great fit for my Bushmaster XM-15 as I started making a few upgrades to it. I have already changed out the stock and plan to switch out the charging handle and pistol grip next. I don’t think I will add an optic because I kind of like the iron sights on the old-school rifles. If you’re thinking about replacing your drop-in handguard, consider an extended system. Some like the look, and others may not. I like how the rifle looks with the front sight sticking up out of the handguard. It’s an easy process and changes the looks of your rifle.