I recently purchased (from DPMS)a lower parts kit and what I thought was a complete assembled upper. My friend gave me a stripped lower and I assembled it in about an hour. The upper is not assembled. Can I assemble the upper without worry of improper head space setting or does DPMS have the head space set when they ship the parts out? If I can assemble the upper without having to worry about head space I could save myself $65-$75 to pay a gunsmith to do it. Thanks in advance for any advice.
On a side note me and a buddy ordered parts from DPMS on Jan. 13 and the parts did not arrive until Apr. 11. When we ordered we asked if the kit telescope stock and they told us yes. When the parts arrived I got a regular stock. After calling them several times and being promised that they would be shipped on three different occasions it took approx. 13 weeks to receive the parts.
While waiting for a reply to this question I found this on-line @
http://groups.msn.com/TheMarylandAR15ShootersSite/maintenacefaq.msnw
Q: How do I Headspace an AR-15?
A: Courtesy of LTC Santose
99% of any "concern" about headspacing is based on a lack of knowledge about what headspace is and does. Unless you take a grinder to the bolt, or fire several thousand rounds of ammunition on AUTO, you can't induce dangerous headspace. The Army, which fires a zillion rounds a year has one (1) gage. Gage, headspace, field. That's it.
If you buy commercial barrels and bolts from Bushmaster or Colt's you don't need to worry -- or even THINK -- about headspace. Unless you've fired several thousand rounds of ammunition you don't need to worry -- or even THINK -- about headspace other than an ANNUAL check with the field gage. Reserve units only do it every two years. If the bolt closes on the field gage you fit a new bolt. If it closes you fit a new barrel and use the OLD bolt. If that fails use a new bolt and new barrel. No GO or NO-GO checking, just FIELD. There's no concern about a NEW bolt in an old barrel. Heck it's going to be larger -- no wear -- than the old bolt and there will be less headspace.
Do NOT use commercial gages.
Is this accurate and a trustworthy source?