If I am going to remove my barrel from a new unfired upper to install a free float forearm; do I have to check headspace when reinstalling the barrel?  (I have a quality torque wrench.)  Would it be safe to just torque the barrel down and fireaway?  I have never done this before, but I want to do it myself.

Any advice from seasoned professional would be greatly appreciated.

Thanks,

Joanthan

Headspace was set at the factory. Since you are using the same parts, no headspace check will be necessary.

Headspace in an AR is determined by the dimensional relationship of the bolt and the barrel extension.  The torque of the barrel nut (which secures the barrel assembly to the upper receiver) has nothing to do with headspace in this design.

It is always prudent to have someone check the headspace before firing your AR when a new barrel or bolt combination is installed.  Changing only the handguard will have no effect on headspace.