Reader M.D.W. wrote a very informative article, as far as he went. The newest technology in the air rifle race is the nitrogen piston, replacing the metal spring on the break action guns, both in rifle and pistol format. The nitrogen piston, or nitro piston as it is known, uses the technology of the auto shock absorber. When was the last time that anybody heard of one of those failing? The nitro piston can be purchased as a spare and stored indefinitely on the shelf with no special attention. The major advantage of the nitro piston is no spring bounce after the piston bottoms. There will be no further vibration from the piston section, unlike the spring that still moves slightly back and forth after the piston bottoms. These rifles can hold a Quarter-size group at 25 yards. The muzzle velocities are up to 1,000 fps. With a .22 cal pellet weighing 14.3 grains, the power is in the high 20s of foot-pounds of energy. As anything over 15 is adequate for squirrels and rabbits, these air rifles can help feed a family. After a break-in period , the manufacturers claim a reduction in noise up to 70% over spring action rifles. The barrel shroud doubles as a baffle to reduce noise. Very helpful when stealth is needed. Benjamin/Crosman/Remington and Gamo are the major producers of this type of air rifle. - Carl L.