Free float sight issues?

[GrampaJoel]

I have seen rifles with free float hand-guards rails with the front sight mounted on the leading edge of the hand-guards rail.
As opposed to being mounted on the barrel itself.

My question is.
Won't this cause a distortion of aim if the free floating hand-guard rail moves?
Say it gets bumped?

[Merc1138]

Make sure it's fastened good enough and it shouldn't be a problem. The point of free floating a barrel is so nothing interferes with it shifting your point of impact. You could say the same thing about a scope mount being bumped since that isn't attached to the barrel, but proper mounting prevents that from being a problem.

[sszeto]

A properly installed free float rail won't be move easily.

[Josh3239]

Potentially, but they are made to not move. Usually they are bolted onto the barrel nut and the sight is bolted to the handguards. No more likely to move that a front sight on a barrel.

[Metal God]

Won't this cause a distortion of aim if the free floating hand-guard rail moves?

Short answer , Yes .

Say it gets bumped?

Long answer , NO If the rail is installed correctly and is of a good quality you should be able to slam it and it not move . The way you asked the question . you have to say yes . ( if your rail moves , of course your sights would be off )

[GrampaJoel]

Well thanks for the quick replies.
All this info is just what I need!
I looked at the different styles and thought the hand guards were mounted to the upper receiver.
Now I know differently.
Thanks again for educating me.

[Merc1138]

Well thanks for the quick replies.
All this info is just what I need!
I looked at the different styles and thought the hand guards were mounted to the upper receiver.
Now I know differently.
Thanks again for educating me.

Well they are, it's just that the method they're mounted isn't flimsy enough to throw off your point of aim by getting bumped around. If they were, they'd be trash that no one would be willing to use.

[Sam .223]

i've had my front sight mounted on the forearm for a few years now and i have never had to rezero it, even after its been bumped by other guns in the safe, so if you avoid the lower end forearms you should be ok.

[ar15barrels]

I have seen rifles with free float hand-guards rails with the front sight mounted on the leading edge of the hand-guards rail.
As opposed to being mounted on the barrel itself.

My question is.
Won't this cause a distortion of aim if the free floating hand-guard rail moves?
Say it gets bumped?

Best iron sight accuracy IS obtained when the sight is mounted to the barrel and the handguard is free floating.
Most people use their iron sights in a backup role to optics and do not have very high accuracy requirements of their iron sights or tey do not use ammo that is accurate enough to actually SEE the sighting problems.
That is why they do not mind if the sight is moving in relation to the barrel.
Through a course of fire, a typical barrel will wander as it heats up.
By fixing the sight to the barrel, the sight will wander with the barrel and will always be in alignment.
When the sight is fixed to a floating handguard, the barrel wanders out of alignment with the sight.

[P.Charm]

I believe that is the purpose of the free floating handguard. it is meant not to move very easily.

[ar15barrels]

I believe that is the purpose of the free floating handguard. it is meant not to move very easily.

The purpose of the free floating handguard is to eliminate pressure from the sling, bipod of front rest from the barrel.
That way, the barrel can vibrate unimpeded while contacting only the receiver.
The unimpeded vibration is much more consistent than if you were pulling against the barrel with a sling or resting the barrel on a bipod or front rest.
More consistent vibration leads to smaller groups on target.

[LBDamned]

great information in this thread!

On an M&P10, I was contemplating replacing the railed gas block with a low profile gas block and getting a rifle length FF rail...

Based on info here, for function - it would be better to keep the OEM gas block and use a mid length rail to replace OEM hand-guards - correct?

It looks way cooler having longer FF rail... and I suspect the sight wouldn't be off enough to make much difference... but it's a pencil barrel so I'm thinking it might be better to use the railed gas block?

Opinions from those in the know?

[P.Charm]

The purpose of the free floating handguard is to eliminate pressure from the sling, bipod of front rest from the barrel.
That way, the barrel can vibrate unimpeded while contacting only the receiver.
The unimpeded vibration is much more consistent than if you were pulling against the barrel with a sling or resting the barrel on a bipod or front rest.
More consistent vibration leads to smaller groups on target.

Isn't that what I said more or less?

[Merc1138]

Isn't that what I said more or less?

Yes, but he explained the "why" portion.

[ar15barrels]

Isn't that what I said more or less?

No.

You said:

it is meant not to move very easily.

How easy the free float tube moves or does not move is completely irrelevant to the fact that the free float handguard protects the barrel from the stress of touching anything.
It would be fine if the free float handguard was flexible enough to move 1/4" in all directions AS LONG AS THE BARREL NEVER TOUCHED the handguard.