M4 Rifle Combat Reliability - What to do.

Troops make their own changes to improve reliability

M4 failure in Afghanistan caused death of troops but covered up in report as usual.

This is nothing new.  You did whatever you had to do to keep yourself from ending up in a body bag.    I have become enamored with the AK for that very reason.  Yes, is is less sophisticated and the trigger and accuracy have limits but the round is the biggest limitation of the M4.  If you accept that limitation then the AK74 also falls within that profile.  Were I to have no support, access to spare parts, repair facilities, and limited options for maintenance I'd carry an AK.

If you are set on an M4 the first thing I would do is get a complete spare bolt assembly and carry it in a pouch ready for quick replacement.  Beyond that, trigger parts and some other aftermarket parts that improve function are worth spending money on.

Keep your weapon clean.  This is a house to house city gun not really good for desert or extremes like cold.  The small barrel aperture also will create a water vacuum making a risk of firing a round with a water clogged barrel and you know about liquids and compression don't you.  A larger hole/aperture like 7.62 doesn't have that issue.

Clean your weapon regularly and always use top notch magazines.

Magazines: The current best are polymer.  Most of the problems you get with feeding relate to bad magazines with worn springs, feed lips, or ones that are dented and bent.  Aluminum bends the fastest, steel corrodes and is heavy while polymer solves both problems.  Sticky followers are another big issue and are less of a problem with polymer.