View Full Version : Pre Built Upper w/ self built lower. Headspace Question

03-19-2012, 12:14 AM
First time poster.
This is my first rifle I will building and also my first firearm. I am a 'n00b' and just trying to get into the sport with something reliable and durable.

I decided to go with a RRA fully assembled upper half. I will be building my lower using RRA's lower kit. After finishing it should I headspace it? Any suggestions in general?

Parts List:
Tactical CAR A4 Upper Half;
16" Chrome Lined 1:9;
A2 Carry Handle;
A2 Flash Hider;
Chrome Bolt Carrier Group;
A2 Front Sight;
RRA Quad Rail Free Float;
Single Stage Trigger;
Lower Parts kit thru RRA;
RRA 6-Position Tactical CAR Stock Kit, Mil-Spec;

Stripped Lower: To Be Determined; I was thinking a STAG lower or a bushmaster. Will there be any 'issues' using those lowers?

03-19-2012, 12:23 AM
It was headspaced when the barrel extension was put on the barrel.

I wouldn't even worry about it, just run a quality bolt and you're good to go.

Either of those lowers will be fine.

03-19-2012, 12:24 AM
If you are purchasing a Fully assembled upper, chances are it is already headspaced..

03-19-2012, 8:29 AM
Many uppers are built by adjusting the barrel extension threading so that with a specification sized bolt, the headspace will be correct. Some better AR builders go further and check and adjust headspace for a the particulat bolt that will be used on the gun. Either way the gun should be headspaced within limits. There is no practical way to change the headspacing on an already built AR (nothing is impossible but it would be a lot of work), but you can check the headspacing to assure youself that is safe with a simple gauge. If you are looking to build a competition target rifle then you would qlways want to adjust the headspacing to the actual bolt being used, but on a semi auto it is difficult to run chambers tight enough to where the slight difference between one bolt and another would really matter.

03-19-2012, 8:40 AM
Welcome to calguns Bandit!

If you purchased a complete upper with bolt from RRA then your headspace will be good to go. As stated earlier either of the lowers you have listed will be just fine. Don't forget your magazine lock and some 10rd mags too. Have fun with your new toy.:)

03-19-2012, 8:43 AM
Headspace in lay terms is how the bolt fits into the barrel. If you are buying a complete upper that includes a bolt it damn well better be headspaced already.

Your lower half contains the trigger parts. There's nothing to headspace there.

03-19-2012, 9:40 AM
It's headspaced at the factory. You have nothing to worry about. Just go shoot it.