Best Doomsday Weapon!

I have had many people ask me as well as I have read many people asking on different forums about "What is the best weapon to have for the end of the world?" I have had people swear to me that knifes or some sort of sharp metal object is the best since it very low maintenance and highly effective. As a back-up weapon I would highly suggest having some sort of sharp buck knife to use for protection as well as for food gathering. I would not use this for a primary weapon since it has a very short range and may take several attempts to incapacitate an assailant. Your best bet would be to get a firearm and plenty of ammunition for it. Now comes the debate to what firearm to get. The "big two" that are always argued are the AR-15 and the AK-47. The AK-47 is known to be extremely rugged and versatile. I have seen demonstrations where the rifle is left in mud for weeks and when they go unbury it they can shoot it as is with no malfunctions. The problem however is that the AK is not very common in the United States as the AR-15. Every single law enforcement agency issues AR-15’s to their officers all the way from local police departments to the F.B.I so the ammunition as well as parts are very common to find. This is the main reason I would choose this firearm for the apocalypse survivors in the United States. For everyone else in different countries I urge you to get a reliable Russian made AK-47. As far as brands for the AR-15, I am a huge supporter of Colt Firearms. The one thing you should look at is to make sure they fire 5.56 NATO rounds as well as .223 rounds and that it has a dust cover over the ejection port. This will allow for more ammunition options and protection in any dusty climates. The rifle is the ultimate powerhouse to have. They are highly effective at long range, can shot as many rounds as there are in the magazine and are the ultimate weapon.