"Which Free-Float Rail System Should I Buy for my M4?"
The addition of a free-float rail system to any AR-15 pattern carbine is generally one of the first things that many users add to their new rifle. While at one time there were very few makers of such things, in today's market the options can be dizzying. Interestingly, two of the earliest players in this market are still, in my opinion, the top picks for this type of rail.
First, why free-float? As anyone who has shopped for such forends knows, the free-float designs are always the most expensive. Most people then begin to try to rationalize away why they don't "need" a free-float system and why they are better off with a non-free-float rail that simply bolts in to the position of the stock handguards. Usually the first argument they use is something along the lines of "I'm not looking for long-range precision accuracy, so I don't need a free-float rail". This is based, however, off an incorrect assumption that this is the only advantage to a free-float rail, carried over from the idea of free-floating a barrel from the stock on a bolt-action rifle.
Real world advantages for a free-float system on an M4-pattern carbine include the heat-sink properties, the ability to keep sling pressure off the barrel, the ability to mount optics or lasers to the rail, and the overall general increased sturdiness of the free-float system over one that is not.
The selections below are all based on use on a typical carbine-length, or 7"+/-, gas system like that found on the military M4 and the vast majority of commercial variants. All of these products are also available in a 9" length for mid-length gas systems that are ever-increasing in popularity. The suggestions remain the same, with the only differences being the (obvious) increased weight of each due to the longer length.
Also, many users are choosing to install rail systems that extend past the gas block or front sight base (see "A Tale of Two Carbines") and while some of the suggestions below will still apply, there are some other issues to consider when doing so. Keep an eye out for a future article on this subject.
There are 4 options I would consider when choosing a 7.0 length free-float railed forend, and one "also ran" that is listed at the end. Below is a comparison chart of the various rails listed showing measurements, weights, and prices.
Daniel Defense Omega 7.0 This
is a two-piece rail system that utilizes the stock barrel nut on your
rifle and does not require the removal of the front sight base, delta
ring, barrel, nut, etc. It has an integral QD pushbutton sling swivel
with rotation limit on the rear port and starboard side of the rail.
It is 2.43" tall (like all Daniel Defense rails) and 1.90" wide with an
internal diameter of 1.10". It weighs 7.75 oz, but for comparison
purposes to other rails that have their own barrel nut you have to add
back in 2.5 oz for the stock handguard cap, delta ring, and barrel nut
bringing the relative weight to 10.25 oz. The top rail is at the same
height as the flat top upper and extends back over the delta ring to
make a continuous rail with the upper receiver. It's also available in
a "flat
dark earth" finish.
The advantage of
this rail system is in the installation. If you don't want to, or
can't, or aren't allowed to remove your barrel or front sight base,
this rail still allows you to have a free float system. Examples of
this may include a lack of skills, tools, or confidence, administrative
rules on a department or agency owned firearm, or a barrel with a
permanently attached muzzle device that prevents the removal of the
front sight base. There are other manufacturers out there that do
similar but they all weigh more than the Omega.
The
limitation of this rail system is that it's a two-piece (more joints
means more failure points, it's just a fact of life), it's the heaviest
of the Daniel Defense rails (but still lighter than a Larue, even with
the 2.5 oz adjustment). The internal diameter is also one of the
smallest on the market which, on a typical 7.0 application where the
front sight base remains is not much of an issue, but buyers should
still be aware of it.
Daniel Defense Omega 7.0
Daniel Defense M4 Rail 7.0 This
is a one-piece rail system that comes with it's own barrel nut
attachment such that the stock handguard cap, delta ring, and barrel
nut are discarded and installation requires the removal of the barrel
in order to remove these parts. It does not have any provision for
sling attachment an as such if the user wants to attach a sling to the
rail you have to add one (Daniel Defense makes several).
It is the typical Daniel Defense 2.43" tall, is slightly wider than the
Omega at 1.94" but has an internal diameter of 1.45". It weighs in at
8.5 oz, but the pushbutton sling swivel adds one oz if you choose to
use it. This rail system is almost a direct 1:1 for weight replacement
when it replaces a stock set of double-heat-shield M4 handguards,
barrel nut, delta ring, handguard cap, and sling swivel. The top rail
is at the same height as the flat top upper but does not extend back to
make a continuous rail. The threaded portion at the rear of the rail
is attached to the rail itself via 4 spot welds. Like the Omega, it is
available in a "flat
dark earth" variant.
The advantage
of this system is the light weight and the one-piece construction
(alright, it's really multiple pieces, but the rail itself is made up
of only one). The fact that it is a 1:1 weight replacement for stock
parts is a very nice feature. It also has the largest internal
diameter of any of the 4 listed here. Again, this may not be an issue
for your application.
The limitations of
this rail system include no sling-mount and the lack of a continuous
top rail. Some also consider the lack of a locking handguard/barrel
nut at the rear to be a liability and cite the possibility that torque
on the rail could loosen the barrel (although I've never seen it happen
personally). Others point to the spot welds at the rear as being
potentially weaker than other attachment methods and/or think they are
"ugly" (obviously a very subjective matter, and frankly entirely
pointless).
Daniel Defense M4 7.0
Daniel Defense AR 15 Lite Rail 7.0 This
is a one-piece rail system that comes with it's own barrel nut
attachment such that the stock handguard cap, delta ring, and barrel
nut are discarded and installation requires the removal of the barrel
in order to remove these parts. Again, this rail is 2.43" tall like
the other Daniel Defense offerings, but is 2.06" wide with a 1.23"
internal diameter. This makes it the "fattest" of all 4 rail systems
but it has an internal diameter second only to the M4 rail. It also
weighs in at 8.5 oz with an added one oz for a bolt-on sling attachment
if you desire it. The top rail is at the same height as the flat top
upper and extends back to make a continuous rail. The bolt-up portion
at the rear of the rail is attached to the rail itself via welds.
The
advantages of this rail include the light weight of the M4, the
continuous rail of the Omega, plus a locking ring mounting method that
prevents the possibility of torquing the barrel loose.
The
limitations of this system used to be the higher price, but according
to the Daniel Defense website it now goes for the same price as the M4
rail. Be careful when shopping, however, as some retailers are still
listing it at $50 more than the M4 rail. Again, some may point to the
welded construction as a negative but that is theoretical at best.
Also, the lack of a sling swivel is viewed by some as a negative.
Daniel Defense Lite Rail 7.0
LaRue Tactical 7.0" Handguard LT15-7 This
is a one-piece rail system that comes with it's own barrel nut
attachment such that the stock handguard cap, delta ring, and barrel
nut are discarded and installation requires the removal of the barrel
in order to remove these parts. The Larue rail is 2.22" tall, 2.00"
wide, and has an internal diameter of 1.20". It weighs in at 11.87 oz
making it the heaviest of the 4 rail systems here. It includes a QD
pushbutton sling swivel at the rear port and starboard sides of the
rail, and this swivel does have the built-in rotation limit. The top
rail is at the same height as the flat top upper but does not extend
back to make a continuous rail. The threaded portion at the rear of
the rail is attached to the rail itself via "glue", but be aware that
calling the attachment method "glue" or "epoxy" disregards and
downplays the strength of the attachment. The mounting method also
includes a rotation-limiting system to keep the rail and barrel nut
from turning.
The advantages of this
rail system include the integral sling swivels, the locking mounting
system, and the short overall height. The height is made up at the
bottom of the rail which allows the shooter to get their grip higher
and closer to the barrel itself. It is also the least expensive of the
4 rails listed here.
The main limitation
is the weight. Also, the small internal diameter may be an issue for
some. The "epoxy" attachment method between nut and rail also has it's
detractors just like the Daniel Defense welds have their detractors.
Larue Tactical 7.0 LT15-7
Summary To sum up: I would choose
the DD Omega if I was not allowed to, or was unable to, remove the
stock parts required for installation of the other rails. I would choose the DD M4 rail if weight, simplicity, width, and internal diameter were critical for me. I would choose the DD Lite rail if weight and a continuous top rail were critical for me. I would choose the LT rail if price, overall height and an integral sling swivel were critical for me.
Also Ran...
Calling the JP Rifles Viking Tactics free-float tube an "also
ran" is a bit of an insult. It alludes to it being a lower-quality
part or a less practical system, neither of which is the case. I refer
to it as an "also ran" because it's not, strictly speaking, a
free-float rail system in the same vein as the others above. It is a
free-float handguard, and it does have the ability to attach rails, but
it is not the traditional 4-rail system that most of us have come to be
familiar with.
This is a one-piece rail system that comes with it's own barrel nut
attachment such that the stock handguard cap, delta ring, and barrel
nut are discarded and installation requires the removal of the barrel
in order to remove these parts. It has a 2.00" external diameter and a
1.75" internal diameter, and weighs 10.5 oz. Since it is round, the
height and width without rails is the same. Which brings us to the
rails. The JP Vtac tube has slots milled at 12:00, 1:30, 3:00 etc.
around the rail. The slots allow the attachment of a piece of rail
with the length determined by the end-user. They can be had in 2"
sections, 4" sections, or a full-length section for attachment to the top
rail. Attaching the top rail brings the height even to that of the
flat top upper such that various back up iron sights or optics can be
mounted. If one wishes to mount only a front sight and otherwise keep
the tube clean, there is also a piece of rail for that. Finally, there is a
sling stud attachment which
can be placed anywhere the user would like for a customized sling
position or for mounting a bi-pod to the bottom of the rail.
The advantages of this system are that it is completely
user-configurable such that rails and sling swivels can be placed
wherever required, and only where required. It is also extremely
inexpensive with the basic rail system selling for $100+/- less than
the others listed here. Of course, the price starts to climb as you
add rails, and depending on how many you add it can quickly more than
double the cost of the system as a whole.
The main limitation is, again, weight. The basic tube with no rails is
lighter only than the Larue above, and once rails and swivels are added
it quickly becomes the heaviest option. In addition, since the rails
are added by screw mount this becomes another potential failure point.
JP/VTac Modular Hand Guard for Carbine Length Gas System on M15 Rifle
