Can someone tell me what this means and how to check for it?  I'm planning on building an upper from the ground up and would like to know how to check for proper headspace when I'm complete.  Thanks for the help.

Get some headspace guages, remove extractor and ejector from bolt. should close on " go guage " and not close on " nogo guage ".

Thats the short version.

But another vital thing is to get a manual, the military manual would be adequate ( Marine service manual is a little more in depth than the generic) And they are otherwise helpful for general stuff also.

Headspace ga. set available from Brownell,s ( Get the catalog, just do it ) Midwayusa.com should have them also.

Travis F.

It's a measurement from the bolt face to the shoulders in the chamber.  There are guages, which simulate the shape of a cartridge, that will measure for excess or below minumum head space.

Too little headspace can cause reliability problems.  And too much headspace can cause cases to rupture.  It is important to have it checked for safety.

just make sure you get the correct gauges for the chamber that it cut for, either .223 or 5.56 NATO.....both are different gauges. most of the ARs out there are 5.56 types, some will have the calibers stamped on the barrel. but if not, call the manufacturer...if you get the Military 5.56 gauges, you won't need to take out the extractor or ejector.

from another post, someone stated that FULTON ARMORY has the USGI gauges

So what do I do if I have excessive or too little headspace?  Is it something that I can adjust myself or is it something a gunsmith has to do?  Bushmaster says all of it's barrels come properly headspaced.  So does this mean I'm good to go with one of their barrels?  Does Colt headspace it's barrels before they ship them out?  So for all the questions but I just want to make sure I understand everything I need to know when it comes to building a rifle.

99.99% of the time a new bolt and new barrel from reputable suppliers are fine.  Many people get erroneous indications from headspace gauges.  Semi-autos are set up somewhat looser than bolt actions ON PURPOSE--to allow smooth chambering and extraction.  If you are going to check headspace, do so with a gauge made specifically for the M16.

If you are assembling your rifle from new parts, just go shoot it.

How is headspace actually adjusted then?  Is some part ground away?

that only includes there completed uppers, if you buy a complete upper from them then you don't need to have it headspaced or their rifles........you can build a complete upper from pieces and parts, but considering the amount you're going to spend on those parts, plus the tools you'll need to buy, and your time, you would be better off buying a complete upper from them, or a rifle.

for warranty purposes, I would buy a AR rifle from RRA, BUSHMASTER...putting a gun together or puttting together a "parts gun" and finding out something doesn't work, you're the one that will have to put more money into it to get it right.

It does not matter whether the barrel is assembled onto the upper or not, the headspace cannot change.  The bolt locks up into the barrel extension.  The bolt carrier and upper receiver are just along for the ride, they don't affect headspace.

I have assembled, rebarreled, torn down and reassembled many AR15's.  I have not seen any headspace problems with new parts.