Why Free Float handguard?

[funkfool]

OK - I was at an shoot recently and was talking with the guys there and was told that using a GI sling on a standard configuation AR (heat shield then the front sight with the sling mount) can warp the barrel and affect the POI.
Is this why you go to a free float handguard?
In addition to the weight and cooling issues... and prices... are they all about the same?
Or what is your personal opinion?

[Hannu]

Advantages of a free float tube :
-Better general accuracy with different loads
-Better accuracy consistency with different loads
-Much better group-to-group consistency
-Much smaller POI shift when supporting rifle different ways
-Smaller POI shift with different loads
-Smaller POI shift when adding or removing accessories (like flashlight, bipod)
-Better barrel cooling with certain models

Disadvantages :
-Price
-Worse barrel cooling with certain models

About price, weight etc. all free float tubes are really not the same

I have only had free float AR-15 rifles since 1994.

[cowboykjohnson]

^^^ that pretty much sums it up.

[Circuits]

Any pressure on the barrel can both minutely warp it, and change the harmonics. These are truly tiny changes, but at 100+ yards, that can translate into visible changes in POI.

A proper free-float prevents the forestock (handguard for AR's) from contacting the barrel at any point, and usually moves the sling swivel to the handguard, instead of its default position on the front sight base.

With no way for the sling or handguard to affect the barrel, the barrel tension and harmonics will now be consistent shot-to-shot (for similar shooting conditions and shot strings) no matter what stance you're shooting from, or whether you're sandbagged, using the sling, or just bracing against your body, etc.

Free-floating eliminates one of the many, many variables which can affect shot-to-shot POI, so it's definitely a good thing, but may not have much effect on your group size if you were already pretty consistent. Once zeroed, a consistent bias is no worse than an absence of bias.

You very well might notice a POI shift when you first switch over to a free-float handguard system, but once you've zeroed again, your stance or bracing should no longer have a measurable effect on your future POIs.

[funkfool]

Once zeroed, a consistent bias is no worse than an absence of bias.

By bias - are you referring to the torque transferred to the barrel by sling tension?
And if so... any long term effects of continually applying that torque?

I am looking at getting a free float carbine length...
LaRue, YHM and a few others seem to get high marks and reviews from others... your suggestions and comments on manufacturers would be appreciated.

[Daniel_187]

Larue or Daniel Defense. Now, do it now before the internet tax

[68Charger]

By bias - are you referring to the torque transferred to the barrel by sling tension?
And if so... any long term effects of continually applying that torque?

torque/pressure applied to the barrel by any source...the sling pressure, a bipod that is connected to the bayonet lug, different amounts of weight on the bayonet lug.. they all affect the harmonics and POI

we're not talking permanent changes here- not enough to "bend" the barrel- just minute changes that affect the POI.. even something that touches the barrel without pressure will change the harmonics, which will change where the end of the barrel is in relation to the sights when the bullet leaves the muzzle.

notice the barrel flex in this video- you can see both the M16 barrel flex, and the AK47 barrel flex:
http://www.youtube.com/watch?v=G6BpI3xD6h0

you can't eliminate the flex, but you want to minimize it (important) and make it consistent (more important).. free floating helps make it more consistent.

[funkfool]

ahhh... wasn't thinking of that.
I see.
It is my next project.
Now just need the $ and someone with the tools.

[sniper7]

Buy LaRue, that is all I have on my guns now.

I also had Midwest Industries for the simplicity of their system, I really liked it, but now that I can remove barrels and do the 1 piece free float handguards I have gone to LaRue.

[low drag]

I have a heavy barrel 16" AR that is capable of 1 MOA out of the box with a 4X optic. I've shot it out to 600 yards. I installed a rail and noticed no difference in accuracy.

If you're going to use a VFG/AFG, flash light, bipod etc a rail makes is all easy.