How long have I been around this platform? This will help: 
Many companies selling M4 and AR variants today try to sell a carbine or rifle that may be suitable for plinking cans, shooting gophers etc. but will not hold up to the standards required for hard use and long life with a high round count. Few companies meet the criteria lined out in the TDP of which Colt and FN abide. Bravo Company is one of the very few companies producing carbines and rifles that meet this standard. Others are Daniel Defense, LMT, Noveske. PART II OF THIS VIDEO IS HERE: http://www.youtube.com/watch?v=_q47EG...
Companies that have been proven to not meet this standard of critical criteria are DPMS, Rock River, Bushmaster and Olympic Arms. Now before you freak out, they do work for what most people use them for. The fact is, they do not have many if not any of the criteria outlined here.
Using the analytics feature, it has become quite apparent that this video has found itself emailed among many individuals at both DPMS, STAG and other brands I forego recommending here. It is also apparent that many internet trolls from either these companies or friends of, have taken it upon themselves to write vitriolic, emotional and zealous comments that border on insane ramblings, defending these brands and accusing me of being ignorant of the M4 platform. These comments will no longer be posted, so do not even waste your time. I suggest you spend the time improving your product line.
What I had to address with some individuals: Bushmaster has refused to release any information or certifications regarding materials, specs, etc. Bushmaster does not hold the TDP or design schematics for the M4, but reverse engineers after measuring Colt parts. Every Bushmaster I have handled, owned, seen, or sold, has lacked a STAKED castle nut. Bushmaster does NOT have an "F" marked FSB, or an H buffer. Your barrel is 1/9 NOT 1/7. All MPI and HP of Bushmaster is BATCH tested. etc. Barrels that have been tested by individuals, has shown they are NOT 11595E. They do NOT parkerize under the FSB. Buffer tubes on Bushmaster are COMMERCIAL aka weaker, thinner, cheaper. Sell your Bushmaster for $900 and go buy a Colt. They are shit and the list goes on. Same goes for Rock River, Olympic, and many others. Do the research. Educate yourself.
Some of the TDP: Auto BCG, 8620 BC, Shrouded Firing Pin, Parkerized Exterior, Chrome lined, USGI specs, Mil-spec gas key hardened/heat treated and chrome lined, secure gas key with "grade 8" fasteners properly staked, Carpenter #158 Bolt, tool steel extractor with black insert, Shot peened, MPI(100%), HPT (100%), 4-coil or 5 coil spring, 11595E Certified Barrel Steel, 5.56 Chamber NOT .223, 1/7 twist Barrel, M4 Feed Ramps, "F" Stamped FSB, Taper Pins, 7000 series lower receiver, Mil-spec diameter buffer tube, properly staked castle nut, Properly marked and weighted buffer, "H" "H2" etc. Also included is properly gassed systems with proper gas port size tube diameter and length. There are other facets not mentioned here however these are the biggies.
THE CHART: 
http://www.calguns.net/calgunforum/sh...
http://www.youtube.com/user/DennyDuce...
http://www.facebook.com/Dennyducet
Here are the FACTS:
http://www.m4carbine.net/showthread.p...
Awesome Colt M4 High Stress Test Video (watch both): http://atwar.blogs.nytimes.com/2010/0...
Article on Colt: http://atwar.blogs.nytimes.com/2010/0...
http://www.colt.com/ColtMilitary/Comp... Colt Weapon Systems The true M4.
http://www.m4carbine.net/showthread.p... More discussion on TDP
http://www.m4carbine.net/showthread.p... Discussion on RRA
PSA? http://www.m4carbine.net/showthread.p...
- People buying from PSA are taking a "shot in the dark" that PSA will get it right.
- People recommending PSA usually have no idea what in the hell they're talking about.
- Colt isn't even expensive enough to justify going with another brand.