NOT A NEW INVENTION
Air guns have been around for hundreds of years. Consider that an air gun was brought as a piece of equipment on the Lewis and Clark expedition between 1804 and 1806. Called the Girandoni repeating rifle, this air gun fired a 46 caliber ball at speeds of 800 feet per second, or about as fast as a .45ACP handgun round. This phenomenal rifle had a tubular magazine that held 20 rounds, and each charge of air (the reservoir was in the butt stock) could propel up to 30 balls before needing to be recharged.
To say the Girandoni was ahead of its time is an understatement – it was in fact the first repeating rifle ever fielded by a military force. While the Girandoni was by no means perfect – in fact, it was a rather delicate rifle and prone to breakage – it did prove that an air rifle could compete favorably with conventional firearms both military purposes and the battlefield.
Modern air rifles are an order of magnitude more reliable than even those of a couple decades ago, and far more powerful. Most discount stores feature air rifles of 1000 feet per second velocities for a little over $100, and these are all capable of taking small game and other varmints.