Free Float Rails on AR15

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  • ddn3f

    Member
    Jul 23, 2009
    36
    Lexington Park, MD
    I am looking to purchase my first AR15 and I plan to install free float rails on it. Do you know how much gunshops usually charge for this service? I looked into doing it myself, but I would need to buy some expensive equipment. If it is an expensive job, then I will look for guns with the rails already installed.
     

    JeepDriver

    Self confessed gun snob
    Aug 28, 2006
    5,193
    White Marsh
    They are easy to install.

    The only thing that stops most people is the couple tools needed. You would have to buy the receiver block and wrench which is a bit of a waste for one install.
     

    K-Romulus

    Suburban Commando
    Mar 15, 2007
    2,427
    NE MoCO
    I would also say research some more.

    Why are you free floating? If this is for a carbine, a free float won't really "get" you a lot compared to floating a "precision"-type upper. I hear free-floats can help cool the carbine barrel by acting as a heat-sink, but if you're not shooting 800 rounds/day I don't know if it is worth it.

    I have free floats on my carbine uppers, but only because I needed to extend my top rail at the time. I attended a 3-day carbine class with my old Yankee Hill non-float rails and did fine. Since I sank the money into the free float, I keep them, but I probably wouldn't do it again. CDI factor is there, though.

    Tools needed to install yourself:
    Bench vise (I got one for $30 off eBay)
    Receiver block (~$40 from Bravo Company USA, Midway USA, Brownells, DPMS,etc)
    . . . .(you can also get by with two small pieces wood instead of a block. I did that once, but heard it could be bad for the receiver.)
    AR15 wrench (~$30 from Brownells, Bravo Company, Midway USA, DPMS, etc)
    1/16"(?) pin punch for gas tube roll pin
    Snap-ring pliers, or two pin punches and a pencil, or a Dremel cutter to remove the delta ring
    Foot-pound torque wrench (optional)

    AR15.com has a great "do it yourself" forum that explains how to remove your barrel and install different makes of free floats. If you can change the oil in your car, you can install the free-float yourself (I've done three).

    Here's a link to the Omega Rail: http://www.danieldefense.com/?page=shop/browse&category=railsystems_omegarail $279 :eek:
     

    mayor_quimby

    4+4= Jello
    Nov 19, 2008
    4,602
    The omega rail is a little cheaper when you sign into Brownells....

    I have 2 one for my full length and mid length.. so far so good.
     
    I would also say research some more.

    Why are you free floating? If this is for a carbine, a free float won't really "get" you a lot compared to floating a "precision"-type upper. I hear free-floats can help cool the carbine barrel by acting as a heat-sink, but if you're not shooting 800 rounds/day I don't know if it is worth it.

    I have free floats on my carbine uppers, but only because I needed to extend my top rail at the time. I attended a 3-day carbine class with my old Yankee Hill non-float rails and did fine. Since I sank the money into the free float, I keep them, but I probably wouldn't do it again. CDI factor is there, though.

    Tools needed to install yourself:
    Bench vise (I got one for $30 off eBay)
    Receiver block (~$40 from Bravo Company USA, Midway USA, Brownells, DPMS,etc)
    . . . .(you can also get by with two small pieces wood instead of a block. I did that once, but heard it could be bad for the receiver.)
    AR15 wrench (~$30 from Brownells, Bravo Company, Midway USA, DPMS, etc)
    1/16"(?) pin punch for gas tube roll pin
    Snap-ring pliers, or two pin punches and a pencil, or a Dremel cutter to remove the delta ring
    Foot-pound torque wrench (optional)

    AR15.com has a great "do it yourself" forum that explains how to remove your barrel and install different makes of free floats. If you can change the oil in your car, you can install the free-float yourself (I've done three).

    Here's a link to the Omega Rail: http://www.danieldefense.com/?page=shop/browse&category=railsystems_omegarail $279 :eek:

    A torque wrench is not optional. To do the job correctly you must apply the prescribed amount of torque to the barrel nut.

    2 pieces of wood subbed in as a receiver block is NEVER a good idea. It is definitely bad for the receiver. To properly tighten a barrel nut you need to apply between 50 and 90 foot pounds of torque to the barrel nut. So you are essentially twisting the receiver by applying this torque. If not properly supported it could be damaged.
     

    CKOD

    Active Member
    Jan 30, 2009
    348
    A torque wrench is not optional. To do the job correctly you must apply the prescribed amount of torque to the barrel nut.
    ...
    To properly tighten a barrel nut you need to apply between 50 and 90 foot pounds of torque .
    ...


    While it definitely helps to know when you got to the 50 ft-lbs (thought my yhm instructions said 40, but cant remember offhand) I dont see it as being 100% needed *IF* you are familiar with torquing bolts down in other applications (automotive comes to mind) Since you must line up the gas tube hole anyway. 50-90 is quite a large range, and I'd say its perfectly reasonable to think someone couldnt torque a bolt to 70 ft-lb +/- 20 by hand w/o a torque wrench.

    This isnt arfcom, your rifle wont form a critical mass and detonate with the intensity of a thousand suns if you dont use a torque wrench, and the proper $500/gram grease for your threads.

    That being said, Ive heard some people say that their rifle shot better with a lower amount of torque on the barrel nut (still enough, just to the low end of the range) vs a higher amount. And given that the reciever is aluminum, there is no reason to put more torque on the reciever then it needs, and a torque wrench would help you out by setting it to the minimum, torque it down, then advance it to line up the gas tube hole.

    Would I borrow or rent (for a low cost) a torque wrench to put together a single AR if thats all I was planning on doing? Yes. Would I buy one if thats the only thing I'd use it for? Nope, and I wouldnt feel bad about it.
     

    K-Romulus

    Suburban Commando
    Mar 15, 2007
    2,427
    NE MoCO
    While it definitely helps to know when you got to the 50 ft-lbs (thought my yhm instructions said 40, but cant remember offhand) I don't see it as being 100% needed *IF* you are familiar with torquing bolts down in other applications (automotive comes to mind) Since you must line up the gas tube hole anyway. 50-90 is quite a large range, and I'd say its perfectly reasonable to think someone couldn't torque a bolt to 70 ft-lb +/- 20 by hand w/o a torque wrench.

    This isn't arfcom, your rifle wont form a critical mass and detonate with the intensity of a thousand suns if you don't use a torque wrench, and the proper $500/gram grease for your threads.

    That being said, Ive heard some people say that their rifle shot better with a lower amount of torque on the barrel nut (still enough, just to the low end of the range) vs a higher amount. And given that the receiver is aluminum, there is no reason to put more torque on the receiver then it needs, and a torque wrench would help you out by setting it to the minimum, torque it down, then advance it to line up the gas tube hole.

    Would I borrow or rent (for a low cost) a torque wrench to put together a single AR if that's all I was planning on doing? Yes. Would I buy one if that's the only thing I'd use it for? Nope, and I wouldn't feel bad about it.

    I can tell you my experience with this.

    The .gov tech manual says to torque the barrel nut "30 to 90ft-lbs". Pretty big range? Well, you start by torquing to 30, then keep going just enough to line up the next closest barrel nut indent with the gas tube hole.

    When I did my barrel, I used an inch-pound torque wrench from my bolt-gun tools, thinking it was more or less all the same. :eek: I didn't go over 90 in-lbs in getting the barrel nut on the to right spot (it should have been at least 360 inch-pounds :eek:). It took some effort to even do that much, so from my (limited) mechanical experience it was definitely past the "hand tight + 1/4 turn with a wrench" spec I heard tank mechanics talk about, so I figured I was good. My only prior experience with this issue was watching a gunsmith replace an Ar-15 barrel; he didn't use a torque wrench, either.

    I guess I got lucky; soon after the replacement I attended a 3-day, 2400 round carbine class. No issues during the class with my "tier 2" rifle. Two years later, everything is still A-OK. I am in the process of getting a ft-lb torque wrench to get things squared away, but everything has worked out so far.

    Oh, yeah: I used Teflon bike grease on the threads. :D I've taken off the barrel a couple of times for other foolishness and everything was still A-OK.
     
    the 50 -90 range is to properly line up the spline on the barrel nut. The actual procedure is to tighten and untighten the barrel nut 3 times to seat the barrel nut. I didn't make this up. Clint McKee told me - and he knows a little bit about ARs. With free floats I usually tighten to 50 and then increase in 5# increments until the 60 to 70 range. It all depends on the feel.
     

    Kevp

    Ultimate Member
    Apr 17, 2008
    1,874
    I would also say research some more.

    Why are you free floating? If this is for a carbine, a free float won't really "get" you a lot compared to floating a "precision"-type upper. I hear free-floats can help cool the carbine barrel by acting as a heat-sink, but if you're not shooting 800 rounds/day I don't know if it is worth it.

    I have free floats on my carbine uppers, but only because I needed to extend my top rail at the time. I attended a 3-day carbine class with my old Yankee Hill non-float rails and did fine. Since I sank the money into the free float, I keep them, but I probably wouldn't do it again. CDI factor is there, though.

    Tools needed to install yourself:
    Bench vise (I got one for $30 off eBay)
    Receiver block (~$40 from Bravo Company USA, Midway USA, Brownells, DPMS,etc)
    . . . .(you can also get by with two small pieces wood instead of a block. I did that once, but heard it could be bad for the receiver.)
    AR15 wrench (~$30 from Brownells, Bravo Company, Midway USA, DPMS, etc)
    1/16"(?) pin punch for gas tube roll pin
    Snap-ring pliers, or two pin punches and a pencil, or a Dremel cutter to remove the delta ring
    Foot-pound torque wrench (optional)

    AR15.com has a great "do it yourself" forum that explains how to remove your barrel and install different makes of free floats. If you can change the oil in your car, you can install the free-float yourself (I've done three).

    Here's a link to the Omega Rail: http://www.danieldefense.com/?page=shop/browse&category=railsystems_omegarail $279 :eek:

    There are a lot of misnomers regarding free floating barrels on carbine ARs. I went through this in dealing with proposed requirements for free floating rail handguards in the military. A carbine, in this case the M4, is an assault rifle not a precision rifle. I had a proposed requirement to install free float rail handguards on M4 carbines come to me for action. The justification was one based on accuracy which could not be substantiated based on mission. There are military and law enforcement organizations that, based on mission, have a requirement to achieve the maximum amount of accuracy out of their carbines. We are talking accuracy in terms of shooting a quadrant of the head vs. a head shot. You can make an arguement there for free floating a carbine.

    The real rationale for using a free float rail system on a carbine in general purpose military and LE applications has nothing to do with accuracy of the rifle- it is the ability to maintain zero of an IR laser aiming device attached to the free float rail handguard on a carbine. The capability that an IR laser combined with night vision devices provides in fighting at night is incredible. For those that don't understand this capability, you can face shoot a bad guy from the hip with a properly zeroed laser. The Knight's Armament RIS/RAS has a tendency to loosen up and cause a shift in zero on attached lasers. It is case where the requirements generation establishment for the general purpose forces has total missed the boat. It is not a must-have for the recreational shooter unless you are shooting competitions where you need to get every bit of accuracy out of your carbine....and they look cool. ;)
     

    smokey

    2A TEACHER
    Jan 31, 2008
    31,412
    There are a lot of misnomers regarding free floating barrels on carbine ARs. I went through this in dealing with proposed requirements for free floating rail handguards in the military. A carbine, in this case the M4, is an assault rifle not a precision rifle. I had a proposed requirement to install free float rail handguards on M4 carbines come to me for action. The justification was one based on accuracy which could not be substantiated based on mission. There are military and law enforcement organizations that, based on mission, have a requirement to achieve the maximum amount of accuracy out of their carbines. We are talking accuracy in terms of shooting a quadrant of the head vs. a head shot. You can make an arguement there for free floating a carbine.

    The real rationale for using a free float rail system on a carbine in general purpose military and LE applications has nothing to do with accuracy of the rifle- it is the ability to maintain zero of an IR laser aiming device attached to the free float rail handguard on a carbine. The capability that an IR laser combined with night vision devices provides in fighting at night is incredible. For those that don't understand this capability, you can face shoot a bad guy from the hip with a properly zeroed laser. The Knight's Armament RIS/RAS has a tendency to loosen up and cause a shift in zero on attached lasers. It is case where the requirements generation establishment for the general purpose forces has total missed the boat. It is not a must-have for the recreational shooter unless you are shooting competitions where you need to get every bit of accuracy out of your carbine....and they look cool. ;)

    hey kev, how much affect does pressure one way or another(inconsistencies in holding/resting the rifle) have on an AR without a free-float tube? i'm guessin it's nothing you'd notice unless using properly worked-up handloads and unless you were a good enough shot to not make those mistakes in the first place. what kind've actual real-world difference in accuracy could one expect moving from something like a utg quadrail to a good floating one?
     

    Russ D

    Ultimate Member
    Nov 10, 2008
    12,029
    Sykesville
    bump cause i'm still curious

    Honestly it would be minimal unless the UTG rail was not installed properly. It's hard to give a good estimate in terms of inches but I'm guessing the difference would be small if any. UTG rails suck because they are not made well, not so much the effect they would have on accuracy.
     

    Kevp

    Ultimate Member
    Apr 17, 2008
    1,874
    hey kev, how much affect does pressure one way or another(inconsistencies in holding/resting the rifle) have on an AR without a free-float tube? i'm guessin it's nothing you'd notice unless using properly worked-up handloads and unless you were a good enough shot to not make those mistakes in the first place. what kind've actual real-world difference in accuracy could one expect moving from something like a utg quadrail to a good floating one?

    Give me a break, I was hunting. It can make a difference, in fact, cranking on a sling that is attached to one of those mounts in the front sight post can make a difference. I can't tell you what kind of difference you'd see in changing- it depends on how loose that UTG is and what kind of firing positions you are using. I'd change it anyway- aren't they Chinese-made? I wouldn't put anything that isn't top notch on something I might have to trust my to. Just the way I look at it.
     

    JeepDriver

    Self confessed gun snob
    Aug 28, 2006
    5,193
    White Marsh
    Resting a non free floated barrel on either a wall, sand bag, car hood or anything else does cause barrel movement and POI shift.

    I can take my hand, and with very little pressure cause the barrel on my 20" Gov Profile barrel to move significantly, same goes for my 11.5" barrel. While simply resting the barrel on something may not cause movement you can see, it will change your POI. You can easily shift the POI an inch at 100 yards by simply resting the barrel/hanguards on something.

    For general plinking, not an issue, but for Zombie's that inch can make the difference. Moving out past 100 yards and getting into the ranges the AR platform is capable of that POI shift becomes a serious problem.
     

    Russ D

    Ultimate Member
    Nov 10, 2008
    12,029
    Sykesville
    I see guys at the range all the time trying to sight in rifles with the barrel directly on the bags. On a cold barrel it's not as much an issue until the barrel heats a little and then the POI goes screwy. It pretty much makes it impossible to sight in a rifle.
     

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