How much clearance is needed from the Gas block to the handguard?

[DocMedic]

When looking down the tube of the business end of the rifle, I have about 1.5mm of clearance from the bottom edge of my gas block to bottom of the Free float tube, how much clearance do I actually need to make sure that the barrel doesn’t “bounce” off the Hand guard? And yes I can squeeze the tube downwards and it will hit the bottom of the handguard.

Edited February 27, 2012 by DocMedic

[dmc_md]

I have very little clearance in mine. I don't think it will effect anything in practice.

Darren

[Ragnar]

Sounds like it is too tight to me.

Edited February 28, 2012 by Ragnar

[Braxton1]

Simple answer: Enough that it doesn't hit it during any type of shooting.

If you really wrench on the gun while shooting prone, for example, you'd want to ensure that it doesn't hit.

I personally don't put that much pressure on a forend (without a sling), so minimum clearance would work for me...

[StealthyBlagga]

I can't give you an exact measurement. The stiffness of the barrel will be a big factor - a heavy barrel will whip less than a pencil barrel. I would imagine the whip also changes with barrel temperature to some extent.

If you watch this

of an AR15 barrel whipping when fired, you will get a feel for the magnitude of the movement. This guy's hypothesis is that much of the whip is attributable to the muzzle device; if true, I guess it should not affect the point-of-impact (the gases only hit the muzzle device after the bullet has left the barrel).

I would suggest you put a thin layer of modeling clay around your gas block or inside the handguard, fire the gun and then see if you can see in indentation where the two are making contact. If there is no contact, then life is good.

Edited February 28, 2012 by StealthyBlagga

[DocMedic]

I can't give you an exact measurement. The stiffness of the barrel will be a big factor - a heavy barrel will whip less than a pencil barrel. I would imagine the whip also changes with barrel temperature to some extent.

If you watch this

of an AR15 barrel whipping when fired, you will get a feel for the magnitude of the movement. This guy's hypothesis is that much of the whip is attributable to the muzzle device; if true, I guess it should not affect the point-of-impact (the gases only hit the muzzle device after the bullet has left the barrel).

I would suggest you put a thin layer of modeling clay around your gas block or inside the handguard, fire the gun and then see if you can see in indentation where the two are making contact. If there is no contact, then life is good.

That's brilliant, I'm gonna try that

[StealthyBlagga]

I can't give you an exact measurement. The stiffness of the barrel will be a big factor - a heavy barrel will whip less than a pencil barrel. I would imagine the whip also changes with barrel temperature to some extent.

If you watch this

of an AR15 barrel whipping when fired, you will get a feel for the magnitude of the movement. This guy's hypothesis is that much of the whip is attributable to the muzzle device; if true, I guess it should not affect the point-of-impact (the gases only hit the muzzle device after the bullet has left the barrel).

I would suggest you put a thin layer of modeling clay around your gas block or inside the handguard, fire the gun and then see if you can see in indentation where the two are making contact. If there is no contact, then life is good.

That's brilliant, I'm gonna try that

You are welcome. Be sure to post the results.