Posted on by Gerald Kim

2-piece or free float quad rail: How to decide which quad rail is right for you

2 Piece Drop-In vs Free Float?

Quad rail handguards generally come in one of two form factors: 2 Piece Drop-In or Free Float. The decision to buy one or the other depends on 1) how much effort you want to put into installing the quad rail and 2) how ultra precise you want your rifle to be.

2 Piece Drop-In Quad Rail, as the name implies, comes in two pieces and screws together into place between the AR-15 receiver and front sight/gas block. The tapered end fits into the delta ring, which holds the quad rail in place against the end cap on the rear of the front sight. For more details, please see our AR-15 2 Piece Drop-In Quad Rail Installation Guide

The key selling points of a 2 Piece Drop-In Quad Rail are:

2 Piece Drop-In Quad Rails are typically less expensive

2 Piece Drop-In Quad Rails are easier to install and require no special tools or gunsmithing experience

A 2 Piece Drop-In Quad Rail can be installed by anyone in a few minutes. It requires no special tools, though we do recommend using an AR-15 Handguard Removal Tool.

Free Float Quad Rail differs from a 2 Piece Drop-In Quad Rail in that it attaches directly to the AR-15 lower receiver and does not come into contact with the front sight, and by extension, the barrel. The idea behind this is that a 2 Piece Drop-In Quad Rail, being in constant contact with the barrel, will exert a tiny amount of force on the barrel and will ever so slightly impact the precision of the rifle.

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The key selling point of a Free Float Quad Rail is:

- Free float quad rails do not come in contact with the barrel and thus do not impact the precision of the rifle

Please note that the impact on precision is miniscule and will not make a significant difference for the vast majority of shooters.

The main drawback of a free float quad rail is that installation requires special tools and a more gunsmithing expertise. At minimum, installation of a free float quad rail handguard requires a vise, an upper receiver vise block, a hammer and punch set, and an AR-15 armoror’s tool. Please see our AR-15 Free Float Quad Rail Installation Guide for more details. If you do not have experience installing a free float quad rail, we highly recommend consulting an experienced gunsmith.

To view our selection of AR-15 quad rail handguards, you can follow these links:

Monstrum Tactical 2 Piece Drop-In Quad Rail Handguards 

Monstrum Tactical Free Float Quad Rail Handguards


keywords: Ar 15 rifle m4 2 piece quad rail?