Well, I should have my new non-ban upper for my DPMS AR rifle on the way soon.  I have the old upper sold already and have a question.

Can I safely use the bolt from my old upper with the new one?  Should I get a new bolt for the new upper?  How does one test and adjust headspace on an AR type rifle?

Thanks in advance for any info!

As far as I know, there is no way to adjust head space on an AR, short of putting a bushing in the chamber and recutting it.  Even this may not be possible.

Just put the thing together and either check the head space with your own gauge(s) or pay a gunsmith to do it.  If head space proves to be out of specifications, you will have to swap parts around.  If it checks good, leave everything alone.

In this particular case, the upper is brand new, so I am trying to decide whether to get a new bolt for it or see if my current one will work ok.  My current unit probably has about 3k rounds on it.

In your various opinions should I use my current bolt or quit being a cheap bastard and get one new for $110?

I'm w/ Raf, don't be a tight-wad, get the new bolt to go w/ your new upper (i also agree that ya should sell the old upper w/ the working b/bc/ch in it too, for the same reason, YA KNOW IT WORKS!).

That said you should get yourself a set of go-no go gauges or a field gauge, (I have both) simply to check your new upper prior to "DETONATION" (just kiddin, as mentioned it's probably okay but never hurts to check).

Mike

Ok, message received.  A new bolt assembly is on the way to go with the new upper.  I am giving the old ban-era upper to a friend to build his own AR with.  He will get the bolt that matches as well.

Quoted: That said you should get yourself a set of go-no go gauges or a field gauge, (I have both) simply to check your new upper prior to "DETONATION" (just kiddin, as mentioned it's probably okay but never hurts to check).

To be sure, get the correct gauges for your gun. Here's where there is difference, it's in the chamber sizes. The military 556NATO chamber is larger than the civilian 223Rem chamber even thought the ammo is the same, more or less.

Not so much a matter of chamber size, the main difference in NATO vs SAAMI chambers is in leade, the throat.  

BUT there is a difference in semiauto chambers, which are generally larger, looser, for good feeding.  In addition, they are looser, particularly for military rifles, to allow for ammo that is dirty, bent, not quite sized right, etc.  So, the chambers for AR-15's/M16's are looser for both .223 and 5.56 vs the chambers of bolt actions.  Using regular gauges on an AR-15 will show a new chamber to indicate being nearly worn out.  You must get the proper M16 military type gauge.

The worry about headspace on new uppers and bolts is way overblown.  Unless a bolt AND barrel are both very high mileage it is just not a worry.

The best reason for keeping a bolt dedicated to a particular barrel is that they set up a wear pattern together.  They both wear slightly and obtain a good even fit.  Swapping bolt to a new barrel will make it have to set up a new wear pattern, theoretically causing quicker wear.

If you want to use another bolt and carrier for a while, fine, won't hurt a thing, but I would suggest getting a bolt carrier assembly for each upper.

Well, when I get my evil-enhanced AR assembled, I will try to post  some pics here.  I hope to have the new upper and new bolt here this week sometime.