For most people, the following test will be as interesting for the methods used as it is for the conclusions that were reached.
This presentation was initially shown in May of 2003; the “other comments” page would seem to be especially prescient in light of all the “improvements” that have been made to the AR platform in the years since. Some I fully support, such as midlength gas systems (especially for 16″ barrels), while others (such as poorly engineered “piston conversions”) I do not.
The following sentence is also quite interesting:
“Case extraction and ejection successfully occur as long as the case is held against the bolt face by the residual chamber pressure while the extractor lifts and returns to position.”
Although it is easy to put together an AR-15 from an amalgamation of random components, it seems lost on many that the AR-15 is a system that must work in harmony. The AR-15 is more than the sum of its parts. Many commercial manufacturers have taken it upon themselves to “improve” the system in order to make it work with cheap ammo, or be cheaper to manufacture, or simply because they do not understand why something was done a certain way. Such actions can reduce the service life of the weapon and compromise reliability.