Catches then have so much tension that the magazine fails to push past and fully seat. Normally not a problem as the magazine is gripped tightly anyway.
What happens is on three shot burst, the magazine eventually slightly dislodges and a round fails to chamber.
When changing magazines quickly, this is a common problem.
Also, I found out in very dry, dusty climates, solvent clean and allow to fully dry with no residue, then use only a dry lube, like Action Magic. The talcum sand of Iraq won't stick to it.
If you do a good job of setting up your weapon, you can run 500+ rounds without a jam or misfire.
It is critical to keep the ejection port cover closed at all times and the muzzle capped, bag your barrel.
I have minimal misfires and jams and only after excessive use. The M-16 is a terrific weapon, I will choose it in a fight anytime over an AK.
Thanks for all the great info gang! This turned into a great thread.
My Saiga .223 has never failed to chamber, I feed it 5.56 and various .223REM, brass, steel case, surplus whatever I put in it...