AR Gas Tube Free Float How Critical

[M25BeastShooter]

How critical is the free float of the gas tube on the AR rifle to making the rifle accurate. I have a .308 AR it shoots .440 through 1.5" at random using the same load. When cleaning the rifle I noticed that the gas tube in the upper had no free play in it. I have built numerous NM Ar-15's all shoot consistently .5-.75" and in everyone the gas tube has considerable free play.

I tore the rifle down and slightly "adjusted" the tube eliminating the binding/pressure point on the tube. It now has "free play" in the upper where you can easily wiggle the tube in the upper.

Any thoughts or similar solutions? I'm going out tomorrow to bench the rifle again to see if this calms the groups down

 

[Furtaker_.223]

Re: AR Gas Tube Free Float How Critical

The free float tube, I think will not affect accuracy. But the tork of the nut will. 35-40# on the nut should do. As far as the gas tube goes, I think they will have the slightest hint of movement. Not much, If installed properly. If you were to look through a stripped upper reciever, you will see the keyhole just above the barrel opening. As you tork down the barrel nut, you want the hole for the gas tube to be centered in that keyhole. Once all is torked down, and your gas tube is pinned into the gas block you may have a very small bit of movement.

 

[BCP]

Re: AR Gas Tube Free Float How Critical

Could be you, could be the scope. I know that if I concentrate I can stack them one on top of another but when I get sloppy my groups grow to about 1.5".

edit: I would think that if the dinky gas tube really were restricting the barrel's movement it would've bent/snapped long ago.

 

[redirt78]

Re: AR Gas Tube Free Float How Critical

Good info, look forward to more on this.

Any body else think the less weight on your gas block the better?

Example being, not having the front sight or a tactical light mounted to it and keeping all of that kind of stuff on the fore end rails... or am I just crazy?

Adding weight to it has to make some difference, right?

 

[Furtaker_.223]

Re: AR Gas Tube Free Float How Critical

adding weight is not going to affect accuracy. I will help if you are planning to carry it in the field for a period of time. Heavier barrel will help with the accuracy, less harmonics.

 

[M25BeastShooter]

Re: AR Gas Tube Free Float How Critical

Well just finished at the range. It appears that freeing up the gas tube has made the groups very consistent I didn't get any 3 in and two out groups all the groups hovered under 1 MOA with 2 running .4

Just one session but it looks promising

 

[aquinas]

Re: AR Gas Tube Free Float How Critical

It's after the fact, but I was going to tell you the other posters don't know what they are talking about. A binding gas tube will kill accuracy in an AR every time. It is one of THE most important thing to look at when building a rifle. When the bolt is in full battery, there should be free play in the gas tube.

 

[scotharr]

Re: AR Gas Tube Free Float How Critical

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: himaster</div><div class="ubbcode-body">It's after the fact, but I was going to tell you the other posters don't know what they are talking about. A binding gas tube will kill accuracy in an AR every time. It is one of THE most important thing to look at when building a rifle. When the bolt is in full battery, there should be free play in the gas tube. </div></div>
+1

 

[dangerdan87]

Re: AR Gas Tube Free Float How Critical

Free floating gas tube eh? lol

 

[Dtarget]

Re: AR Gas Tube Free Float How Critical

Zediker's books put a properly aligned gas tube pretty high on the list of things to do when assembling an AR....

Paraphrasing: an improperly aligned fas tube WILL negatively affect accuracy

 

[KChen986]

Re: AR Gas Tube Free Float How Critical

Can someone explain the mechanics of how a bound gas tube negatively affects AR accuracy?

 

[scotharr]

Re: AR Gas Tube Free Float How Critical

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: dangedan87</div><div class="ubbcode-body">Free floating gas tube eh? lol </div></div>
not free-floated, "non-binding." think about it, if the gas tube binds or pushes the BCG to one side, that will put uneven pressure on the bolt and impact lock-up.

 

[HOOFER]

Re: AR Gas Tube Free Float How Critical

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: KChen986</div><div class="ubbcode-body">Can someone explain the mechanics of how a bound gas tube negatively affects AR accuracy? </div></div>


the same way a non free floated barrel does. harmonics

 

[acidone]

Re: AR Gas Tube Free Float How Critical

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: lone_soldier</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: KChen986</div><div class="ubbcode-body">Can someone explain the mechanics of how a bound gas tube negatively affects AR accuracy? </div></div>


the same way a non free floated barrel does. harmonics </div></div>

This is true, but it can also effect accuracy if your gas tube is always pushing the bolt carrier to one side or the other.