- Carbines: 6¾ inches (~17 centimeters)
- Mid-Length Rifles: 8½ in. (~21.6 cm)
- Rifle-Length Rails: 12 in. (~30.5 cm)
The size of your quad rail depends on the length of your firearm’s gas system. For carbines, 6-3/4” rails are the standard size. Mid-length rifles require 8-1/2” rails, while rifle-length rails are 12” long.
What is a Quad Rail?
A quad rail is a handguard accessory designed to expand the functionality and versatility of your firearm. To learn more about quad rails, see “What is a Quad Rail?” by 3CR Tactical.
There, you can browse our expansive selection of rail upgrade systems, or discover the types of accessories that can be mounted to quad rails. Continue reading here to learn more about the sizing specifications of these high-performance upgrades.
Are All Quad Rails the Same Size?
No, not all quad rails are the same size, which means you must find a quad rail system that’s compatible with your platform. More specifically, your quad rail must match the length of the gas tube system on your firearm.
Quad rail handguards typically come in lengths of 6.75”, 8.5”, or 12” to fit carbine, mid-length, and rifle-length gas tube systems, respectively. When selecting a quad rail, ensure that you choose the correct length for your firearm.
What is the Inside Diameter of a Quad Rail?
In general, the inside diameter of an AR-15 quad rail is 1.72 inches, or approximately 4.37 centimeters. The inside diameter of a quad rail is an important consideration if you plan to mount muzzle devices or suppressors.
This size provides enough space to accommodate most muzzle devices and 1.5” suppressors. If you plan to use larger suppressors or muzzle devices, it’s essential to confirm the inside diameter of the quad rail you’re interested in purchasing.
What is the Difference Between M-Lok and Quad Rail?
M-Lok is a newer alternative to the traditional quad rail. It is a lightweight, modular system that enables you to attach accessories to the handguard by inserting them into a slot.
M-Lok is much lighter than quad rails and offers more flexibility in terms of accessory placement. On the other hand, quad rails are bulkier but offer a continuous rail for attaching accessories. Ultimately, the decision between M-Lok and quad rail comes down to personal preference and shooting needs. It’s recommended that you test out each configuration on the range to determine which is better suited to your shooting style, your kit, and your needs.
Find the Right Quad Rail for Your Firearm at 3CR Tactical
Upgrading your firearm with a quad rail maximizes it’s functionality for the specific applications that you need it for. At 3CR Tactical, we offer a diverse and curated collection for you to choose from.
From carbine-length to rifle-length, these sytems are constructed from aircraft-quality aluminum, which means that they’re designed to last. Check out our selection to find the right quad rail for your firearm today.
For help finding the right-sized Quad Rail for your AR platform, reach out to our team today.