Here is an example of a .50BMG rifle:
More info is available here
(http://www.barrettrifles.com/rifles/rifles_82A1.htm)
Other Freepers answered your question as to what it is. It is a very serious weapon, no doubt. Why are you being asked about it?
Texas squirrel rifle. We have really big squirrels..
the 50cal Browning Machine Gun has been around for a while in one form or another, mounted in planes, tanks, jeeps, crew serve carried etc. A great weapon to fire and big enough to knock down an elephant.
Any rifle that fires the .50 BMG round.
It is a fairly big round, effective at long ranges.
Some of the military uses it as a sniper rifle. Among target shooters, it is the preferred round for very long range shooting....it flies relatively straight at relatively longer ranges than other rounds. For example, the 1000 yard records have all been .50 BMG lately. The bullet itself is heavy, so wind effects are minimized.
It is generally not used for hunting because it makes for a heavy weapon. Some places that offer long range shots use it (plains/savannah sometimes mountains), but in most hunting situations (forest/brush) its range advantages are wasted.
You can go to fcsa.org (fifty caliber shooters association) for more info.
Here is an example of a .50BMG rifle:
More info is available here
(http://www.barrettrifles.com/rifles/rifles_82A1.htm)
Owl_Eagle
" WAR IS PEACE
FREEDOM IS SLAVERY
DIVERSITY IS STRENGTH"
Do you know what GOOGLE is?
The Browning .50 caliber machine gun was created by John Moses Browning, the most inventive of all American firearms designers. The machine gun was created for the United States Army 80 years ago and it is still in service today.
Orignially the machine gun was made in both watercooled and aircooled versions, the aircooled version is the one still in use.
About 25 years ago, a handful of companies started making bolt action and semi-automatic rifles to fire the .50 BMG cartridge. There are a considerable number of long range target shooters that enjoy shooting these kinds of rifles.
The cartridge itself is a very large round, the full metal jack bullet is about 750 grains heavy, especially considering that many deer rifles of the .30 caliber area shoot 140 to 180 grain bullets.
Many aircraft the USA had in WWII used the aircooled BMG as main armament, both fighters and bombers.
There is no recorded use of one of a .50 BMG gun of any configuration used in a criminal attack in America but that has not stopped an all out campaign to ban them by various gun confiscation groups, whose claims are often outright lies.
It should be alarming to anyone that these VERY EXPENSIVE target rifles, never used in crime, are under attack by gun control/confiscation groups. These people really just want the guns rounded up in America and all of us forceably disarmed.
There are some good reasons why gangstas do not buy nor use these rifles in criminal attacks:
Cost: cheap single shot versions: four grand and up
Weight: average of a decent target rifle version is 36 pounds or so.
Length: four feet long or more
So, no gangsta is going to plunk down four thousand dollars for a very heavy rifle that he can't tote or even shoot out of a car window. So ask yourself, why the screaming over banning them? Good question.
Join the NRA today and fight these groups that seek to disarm us, not only of target rifles but our very right to defend ourselves from criminal attack.
They don't really shoot down airplanes, you know.
It is used for putting a thumb in the eye of Sarah Brady and her distemperate termagants.
It uses the same ammo as the .50 cal MG. The best know is the Barrett. The "One Mile Club" uses them to shoot targets literally a mile away.
Snipe Moose at 1000M!
"Fifty-caliber Browning Machine Gun" is the ammo.
a .50BMG is any rifle that fires this round. They are big, heavy, expensive, and accurate to a great range. Great sniper rifles, and great for extreme-range sports shooting.
And hunting bunnies.
http://www.auctionarms.com/search/displayitem.cfm?itemnum=5934297
.50 bmg for sell
With the new keyword system, this will still appear to all the banglist readers even if shifted to chat, and the poster will continue to get plenty of responses.
Kitty will show you...
Good Luck with the election!
The prototype rifle firing the .50 caliber BMG came into being in WWI as an antitank weapon.
It was developed by the Germans to counter the entry of British tanks onto the battlefield.
This was the 13mm Mauser T-Gewehr, which is technically a .503.
During WWII the Russians introduced the 14.5 mm Soviet PTRD anti-tank rifle firing a 930 grain round with a velocity of 3,230 fps. This is technically a .559 caliber.
The actual .50 caliber sniper rifle as we know it came into being in the 1950's through the modification of the PzB 39 for a .50 BMG barrel and receiver. This rifle saw limited service in VietNam, but it precipitated the development of two anti-personnel weapons - both firing the .50 BMG ammo.
The Marine Corps took the smart route with a bolt action for increased accuracy, and the Army went with a gas operated semi-automatic for increased rate of fire ("spray and pray").
Although no firm data supports the idea, rumor has it that the need of the Afghan rebels for defense against the Soviet Hind helicopters kept our heavy gun development and production alive during the years of that conflict.
You are no doubt familiar with the success of our sniper teams using these weapons in both Desert Storm and the ongoing conflict in Iraq so I won't expound on that issue.
It could be said that the .50 caliber is a military weapon, and that would be correct - so is the .30 caliber.
Outside of it's military uses, the .50 caliber sniper rifle is used by many gun enthusiasts for big game hunting and pure shooting pleasure.
One Mile: 
Here's a Web address you might find useful:
Fifty Caliber Shooter's Institute
One thing I can add:
If you ever shoot one, you'll be hooked for life!