Free Float vs 2 piece handguard

Discussion in 'AR-15 Discussion' started by MAX4utah, Mar 3, 2011.

  1. MAX4utah

    MAX4utah New Member

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    What is the advantage or disadvantage to either of these handgaurds? I am looking into getting one to replace my plastic triangle handguard. It is a rifle length.
     
  2. mjkeat

    mjkeat New Member

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    Do you have specific HGs you're looking at?

    Free float will give you better accuracy.
     

  3. MAX4utah

    MAX4utah New Member

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  4. JonM

    JonM Moderator

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    open sights you wont notice a real difference other than a slight weight gain.

    scoped you MIGHT see a difference but i doubt it. free floating by itself isnt that much of a gain in gas operated rifles.

    in conjunction with a nice trigger, match grade barrel custom tuned ammunition a really good scope you might get some benefit from a ff tube. free floating is designed to let the barrel resonate freely. however there is a gas block part way down interrupting that harmony. im just not convinced a ff tube has an effect on gas operated rifles.

    maybe someone else has a better explanation. or can convince me im wrong.
     
  5. mjkeat

    mjkeat New Member

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    Thats a heavy rail. Have you looked into the Troy TRX EXT or the VTAC?
     
  6. MAX4utah

    MAX4utah New Member

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    Not yet... I will now though. Thanks for the info!
     
  7. Dillinger

    Dillinger New Member

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    This is a thread I have been meaning to start, but have shyed away because I don't have the time to do it properly right now, I am just slammed with work responsibilities and it's really cutting into my FTF time. :eek:

    In short, you have to define what kind of AR application you are looking at doing the swap on.

    If your weapon is a 16" barrelled, bare bones, SHTF, street to street shooter with 100 yard shots being "of distance" AND you don't intend on putting thousands of rounds through it in a short period of time - than you probably don't need a free float tube, nor will you necessarily "benefit" from what it offers.

    If on the other hand you have the same 16" barrel and you are going to shooting thousands of rounds, that plastic foreend is going to heat up quickly and become uncomfortable. Free floating allows for the heat to
    dissipate quickly and keep it away from the shooter's front hand.

    Okay, that takes care of the basic application models.

    If you want to shoot at distance ( varmint hunting, target shooting at 400-500 yards, Tactical Support Weapon ;) ) you need a free floated fore end for your weapon. And here is why.

    As was indicated above, everytime a round is fired there are harmonics that are introduced to the barrel from where it is attached to the front of your receiver all way up to the point the round and gas pressure leave your barrel.

    Harmonics are introduced on three axis (X, Y, & Z). You have torque from the bullet hitting the rifling and wanting to reverse twist the barrel as opposed to the bullet entering the rifling. You have back pressure from the gas explosion behind the round as it initially becomes "blocked" by the rifling and doesn't immediately want to start spinning ( an object in motion tends to stay in motion thing - in this case the bullet is not spinning and just wants to go forward ). And then you have "barrel waiver" as the round gets further down the rifling, develops it's spin, but is much further away from the lock down point of the front of your receiver ( much like you could use a crowbar on a man hole cover, but couldn't lift it with a pair of pliers = leverage ).

    IF your barrel can react to those X, Y, & Z variables the same way everytime you pull the trigger, your group sizes will be more accurate and your overall accuracy will be better. That is why any competition boltgun has a FREE FLOATED barrel.

    Now, if you have X, Y, or Z being influenced by adding tension from a sling, bracing the fore end across the roof of a car hood or the like, than the repeated harmonics that the barrel had shown you in previous shots will be altered.

    Think about throwing a rock into a still puddle. The rings move outward at an even pace in 360 degrees from where the rock landed, right? Now, if throw the same rock into the same puddle, but on one side of the puddle is a barrier of some sort, the ripples are going to start the same, but when they encounter the barrier, they will change. Move the barrier slightly and the following set of ripples will also react differently. Remove the barrier all together and the ripples are back to reacting as they did the first time.

    It's all about harmonics and physics of what is going on when you touch off that one round when it comes down to REAL accuracy.

    I hope that helps, I just don't have the time to do this up right with pictures and examples. Sorry. :eek:

    JD
     
  8. Sniper03

    Sniper03 Supporting Member Supporter

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    Dillinger

    Well put! Sometime when we get time we can also do a post on proper selection of bullet weight compared to twist rate and why someone might think they have an inaccurate rifle. I will be tossing this up and maybe start a forum soon. I will share the formula with them to explain why it happens. I know about a month ago some of us posted how to check for barrel twist if you did not know what you had.
    This with the discussion on barrel harmonics is great topics. Especially for the new folks who have never heard of it!

    Great Post Brother! Sorry I missed you at the Shot Show. Saw Scubie there and spent some time looking around and visiting!

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  9. Sniper03

    Sniper03 Supporting Member Supporter

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    Max,

    If you are just wanting a Handguard with the rails on them you might take a look at the Surefire Rifle Length 2 piece unit. The DEA, FBI and other Federal agencies use the Surefire Model M-73 which is the carbine version of the same 2 piece handguard and rail system. They are easy to install but you must re-zero the rifle after installation. Because as Dillinger stated it will change the barrel harmonics by installing. But once you have done the re-zero it will stay the same unless you change something else that has contact or effects the barrel harmonics. The free float requires front sight and barrel removal.

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  10. Quentin

    Quentin New Member

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    Thanks for the excellent explanation, JD! Point well made as usual.

    My applications lean toward your first example, bare bones carbine, so I went with the MOE handguards which are a big improvement over stock units but at a low cost and very low weight. Rails (FF or non) just don't make sense for me but no doubt they do in many other applications. I lean toward JonM's opinion that the accuracy gain of FF just doesn't matter for my shooting which is basically 100 yards on in. Honing my skills and working on my limitations matter much more.

    Anyway, this is not an easy question to answer since there is no single answer. The important thing is to understand the issue and make the right choice for yourself.
     
  11. MAX4utah

    MAX4utah New Member

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    The Surefire looks like a great rail. Im guessing it is a Free Float, it did not specify. I will give that one a hard look and do some reading.

    mj,
    Most of the rife length rails that i have found are in the 15-17oz range, without spending over $300 anyway. There are alot of good options out there, i still have some research to do.

    Thanks for all the input fellas! That was a great post by Dillinger!
     
  12. mjkeat

    mjkeat New Member

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    Thats what I like about the Troy TRX Ext. Theyre just over 10oz and roughly $170 for the 13" version.
     
  13. MAX4utah

    MAX4utah New Member

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    Thanks for all the help on this guys! I just picked up a Surefire M82 rail for my SP1. Cant wait to get it! Got a great deal on it from a servicemen who returned from Iraq.