I think I know the aswers to these questions but I'd like confirmation since Im a FNG to firearms, but what makes a Beowulf more powerful? Is there a huge difference? Is it just a lot more powder behind that .50 bullet? What do you guys think of .45 cal ARs?..........Taipan

The .50 cal has a little more umph behind it.
http://www.hunt101.com/img/149925.jpg

YOu can buy the Beowulf via Cabaellas.  Or direct.

223 and 45 ammo, you can get anywhere.....

You might end up reloading the Beowulf to make it "economical".... just my $0.04 (inflation)

when faced  with newer calibers  i tend to give them a bit of time before i dive into a project like that.  45 ACP is more econmical and a lot easier to find. If it doesn't catch on , you may be stuck with a $600 dollar upper. But who knows ... i've been wrong before.

Are you talking about 45ACP or .458SOCOM as a caliber?  I have the .458SOCOM and it is a hammer.  A buddy of mine has the .50Beowulf and it was pretty good as well.  The ballistics and power are pretty damn close.  I reload all of my rifle calibers so that makes a huge difference in cost of ammo.  Both the .50 and .458 are about $30 per box of 20 rounds.  You can reload them for way less then that.  Both the .50Beowulf and the .458SOCOM load from factory mags were with some of the other calibers you will need either adapted mags or mag well adapters or both!  

The big calibers rule!

I was refering to .45ACP vs Beowulf .50

Lets see.....

What makes a 50 Beowulf more power full?  And is there a huge difference.  Okay....

Standard 45 ACP is a 200gr load going at 900fps, give or take.  The "energy" is 359ft/lbs.  The 50 Beowolf is a 400gr load going at 1800fps.  The engery for it is at least 1400ft/lbs.  The Beowulf get its power from 1) case volume, which leads to velocity 2) bullet weight    Energy is calculated via wieght (in grains) times the velocity and dividied by a constand....

BUT, you won't be able to go down to any "local" shop or a Walmart and buy 50 Beowulf ammo.  Only a few places sell, so far.  It's not like going to buy a box of 308 or 38 Special......