AR-15 has a MUCH bigger boom potential.
Here is one that I have in .450 Bushmaster. The factory ammo is 250grain ballistic tips but my hand loads are 400 grain hard cast bullets. This set up has enough "knock down" to stop any vehicle engine in one shot, same energy at 100 yards as a .50 Beowulf when I use my handloads.
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Next, the AR can be retrofitted with a .22lr or a .22mag conversion bolt. This turns your primary weapon into a small game gun, the most valuable caliber in a self reliance situation.
The 5.56/.223 round that the standard AR15 takes is more commonly available in the US than any other. From military surplus to bulk plinking ammo to varmint and medium game hunting ammo, the .223 will probably be available when other calibers are not, especially since its the standard designation for all US armed forces.
Accuracy- The AR has come a LONG way, especially in the past ten years. My favorite AR for example, has a match .223 chamber and shoots handloads to 1/2MOA.
Here is my shooting partner putting a hole in a coin at 200 yards in one shot with a DPMS AR15, using a Nikon scope and Leupold Mounts.
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Reliability- There is a lot of crap out there about the AR platform being unreliable. Most of it is B/S. I got jams fairly often in Basic because my weapon was to dry. That was remedied quickly at my first duty station. Once the M4 came out, reliability became awesome. In 8 years I only had three jams in my M4 and 1 of them was a pop-and-no-kick jam (bad ammo). We should also remember that the platform Stoner created was designed for a faster burning powder than the military uses in standard M-193 light ball ammo. When Stoner wrote about this he was met with opposition because the Army had already commissioned contracts for the ammo and decided not to cancel them. This is where the idea of low reliability came from.
Mags- most "picky" AR15's are not pick with ammo, just with mags. There are a lot of guys at my range, both Mill and Civ ranges, that find their so-called picky guns work just fine after they find mags that the guns like.
Dirty AR15's???- Not true at all. When I run Three-Gun I dip my entire bolt on Mobile1 motor oil. I'm not kidding, the gun I use for rapid comp likes to run that wet. It may shoot 3,500-5,000 rounds in a day and it does not get cleaned till it's all over.
One size fits all- AR's are modular weapons. As said earlier, they really are the Legos for adults. My favorite is my .450 Bushmaster. Its light, pointable, and has more boom than a target knows what to do with. My wife's however is a LWRC SBR (legal, with permit) in 5.56 because it has the best balance for her. My shooting partner likes his DPMS best because it's bull bbl give it enough accuracy that it can out shoot many bolt guns when using hand loads (sub 3/4 MOA). We all like going squirrel hunting with a .22 bolt conversion. From tree rats to Brown Bear, the AR really can do it all.
I also hunt with the AR. I have a .223 upper that is just for coyote hunting. It has a 4-12 scope for most hunting situations but also has a day visible green laser for those times when he sneaks up closer than you realized and your gun is pointed the wrong way.