AR Sponsor
Posted: 12/16/2010 8:24:19 AM EDT
| I'm looking for people's perspectives on free-float rail systems vs. standard ar-15 hand guards. Aesthetics aside, I'm interested in the pro's and con's and and any positive or negative experiences with either. I have owned rifles with both set-ups and I'm curious how other's compare the two. I currently have a 16" carbine with a 9" DD omega rail over a low pro gas block and a Magpul MBUS sight. I'm thinking about switching back to the standard hand guards since they're lighter. Also, the standard front sight post seems like a more stable, rugged sight since it is pinned directly to the barrel. Thoughts? |
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FF handguards allows your rifle to be more accurate than non-FF handguards. On a non-FF handguard, pressure exerted via a sling, bipod, or even your grip can cause slight changes in POI because the pressure translates from the handguard to the barrel. Since its likely that you're exerting different pressures everytime you shoot, the POI change will not be consistent, giving you non-consistent accuracy.
I do not notice much of a weight difference between a quad rail FF handguard and a quad rail non-FF handguard (A plastic MOE/A2/A1 style handguard will of course be lighter than a quad rail of any type). For me, it's a no brainer to have a FF handguard. |
| My AR currently has an M5 RAS on it. It's not a precision build so a FF handguard isn't needed, actually I wouldn't even use my AR for precision since I have other rifles already better suited for it. I think free float makes a difference in performance at uber long ranges and maybe if you have a lot of crap on your rails. I don't see how pressure from a sling or bipod can substantially change accuracy at the ranges an AR is suited for, especially when the rifle see's more pressure, vibration, and movement from firing than you are capable of producing with your hands. |
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Quoted:
My AR currently has an M5 RAS on it. It's not a precision build so a FF handguard isn't needed, actually I wouldn't even use my AR for precision since I have other rifles already better suited for it. I think free float makes a difference in performance at uber long ranges and maybe if you have a lot of crap on your rails. I don't see how pressure from a sling or bipod can substantially change accuracy at the ranges an AR is suited for, especially when the rifle see's more pressure, vibration, and movement from firing than you are capable of producing with your hands. 
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Quoted:
Quoted:
My AR currently has an M5 RAS on it. It's not a precision build so a FF handguard isn't needed, actually I wouldn't even use my AR for precision since I have other rifles already better suited for it. I think free float makes a difference in performance at uber long ranges and maybe if you have a lot of crap on your rails. I don't see how pressure from a sling or bipod can substantially change accuracy at the ranges an AR is suited for, especially when the rifle see's more pressure, vibration, and movement from firing than you are capable of producing with your hands. OP asked for perspectives. That's my perspective, feel free to correct. |
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My AR currently has an M5 RAS on it. It's not a precision build so a FF handguard isn't needed, actually I wouldn't even use my AR for precision since I have other rifles already better suited for it. I think free float makes a difference in performance at uber long ranges and maybe if you have a lot of crap on your rails. I don't see how pressure from a sling or bipod can substantially change accuracy at the ranges an AR is suited for, especially when the rifle see's more pressure, vibration, and movement from firing than you are capable of producing with your hands. OP asked for perspectives. That's my perspective, feel free to correct. Even at close ranges the difference in POI from standing, to kneeling, to prone, to resting the rifle on something, to resting the rifle on something else, to using a bipod, to using a sling, is pretty big. I have seen this first hand with M14s and ARs. Consistency is key and the pressure, vibration, and movement from firing is always the same. Forces exerted from you or the environment mess with that consistency. Free float doesn't only make a difference in performance at uber long ranges or if you have a lot of crap on your rails. Dustin |
| How big is "pretty big"? If we are talking less than quarter inch or something I find that fairly minute unless you are shooting long range. From my observations the difference between free float and non free float is not very noticeable unless you shoot for super groups, shoot long distances, or love to mount so much shit on your rails it affects the harmonics of the barrel more than the norm. So no the OP is probably not going to notice a substantial POI difference when using standard handgaurds vs free floated provided he doesn't need to squeeze microscopic ass groups out of his AR. |
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How big is "pretty big"? If we are talking less than quarter inch or something I find that fairly minute unless you are shooting long range. From my observations the difference between free float and non free float is not very noticeable unless you shoot for super groups, shoot long distances, or love to mount so much shit on your rails it affects the harmonics of the barrel more than the norm. So no the OP is probably not going to notice a substantial POI difference when using standard handgaurds vs free floated provided he doesn't need to squeeze microscopic ass groups out of his AR. Inches, I've experienced at least a 6" difference from a certain combination and it couldn't have been more than 200 meters. The lighter weight and longer the barrel and the more force applied to it (slinging up or pushing on a bipod are good examples) the more the difference will be. If I get to the range soon (it is about 25° right now) I will show you the difference with a specific rifle. Like I said, consistency is what matters so if you have so much shit mounted on your rails the same way from shot to shot it won't matter. The change in forces (I.E. mounting a shit ton of stuff when you zero and then removing it all later) equals a change in POI. The harmonics of the barrel are to be concerned with if you are shooting super groups. Dustin |
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Quoted:
How big is "pretty big"? If we are talking less than quarter inch or something I find that fairly minute unless you are shooting long range. From my observations the difference between free float and non free float is not very noticeable unless you shoot for super groups, shoot long distances, or love to mount so much shit on your rails it affects the harmonics of the barrel more than the norm. So no the OP is probably not going to notice a substantial POI difference when using standard handgaurds vs free floated provided he doesn't need to squeeze microscopic ass groups out of his AR. How is 2.5 inches at 100 yards 20" A1 Profile barrel. Prone sling pressure. |
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If you rig a GI web sling or a leather sling onto the top of your bicep and get into a knee, prone, or (for me especially) a seated position, the torque exerted on the sling stud is incredible.
If that sling stud is on your Front Site Base instead of a FF handguard, you can bet you'll see a 2-3" difference in POI depending on what position you're assuming. |
| Thanks for all the info. Feel free to continue the discussion since it appears to be a topic of varied opinion. Also, does anyone have any perspective on the front sight issue? Is a standard front sight post more reliable than one attached to a rail since it is pinned to the barrel and not screwed to the rail, which is also independent from the barrel? |
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OP: A Front sight post will have a lesser chance of being broken or losing zero than a rail mounted sight.
Other discussion: So a 2-3" difference in POI can occur because of sling pressure on the barrel? This has to be assuming everyone is using optics; since the compensation can be made using iron sights re-aligning the sight picture and bring POI much closer to POA. At least that is the case when you are trained to shoot irons. Edit: So not to hijack the OP's thread, please continue to educate me here http://www.ar15.com/forums/topic.html?b=3&f=118&t=520155&page=1 |
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Also, the weight thing is really more a factor of which FF you compare to which "standard" handguard. When you include the steel barrel nut, delta ring, and handguard cap, M4 handguards are 9.3 ounces and CAR handguards are 8.2. The lightest free-floats can be lighter than these numbers, and the heaviest ones can be heavier. I really like the Midwest Industries SS series, and lots of other people like the Troy TRX Extreme free floats. Both are lighter than even CAR handguards + standard barrel nut and stuff. Lighter AND more accurate!a
(Source: https://spreadsheets.google.com/ccc?key=0Ajl2UPK0UHPscHdzd2hlZ2hOUXNGblVaTWtaTkYyRFE&hl=en#gid=0) |
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