THE OFTEN UNDERRATED AIR GUN
(Page 3 of 6)
May/June 1981
Excerpt by Jim Carmichel
When air is compressed, heat is generated, and this brings about a peculiar side effect when we shoot air guns. When the chamber pressure in our Red Ryder carbine is at its peak, the internal temperature soars to a momentary high of 620°F. This temperature can ignite residual oil in the chamber, which accounts for the smoke we sometimes see coming from the muzzle and for the characteristic smoky smell we detect when shooting air guns. Occasionally, when too much oil is pumped into an air gun barrel (either accidentally or on purpose), the resulting diesel effect, or oil explosion, raises chamber pressures and velocities well above normal. This explains the harsh jolt you may sometimes feel when shooting a freshly oiled air gun and also explains why it is best to lubricate with special nonflashing oils. Dieseling is hard on guns.
RELATED CONTENT
Air and Sand Lines/Air Supply
January/February 1982
Issue # 73 - January/February 1982
See ...
Making a air powered potato gun toy from piping and wood dowel plunger....
The spring-piston system is used in a wide assortment of makes, models and styles of air guns. The most common cocking arrangement, of course, is the under-lever arrangement used on millions of BB guns.
If a more powerful spring is used, a cocking system employing greater leverage is required. Thus the most powerful spring-piston guns are of the barrel-lever variety in which the barrel itself, by means of a toggle linkage, provides the leverage to cock the powerful mainspring. The barrel is hinged at the breech, just ahead of the receiver-cylinder assembly, and pivots downward during the cocking cycle. This exposes the breech end of the barrel for convenient loading and maintenance. In this type of gun, the rear sight is mounted on the barrel where it is fixed in relation to the front sight.
Another high-leverage cocking arrangement features a separate cocking arm located alongside or underneath the cylinder-receiver. This is the system used on the top tournament-grade air guns, such as the Feinwerkbau Model 300 rifle and models 65 and 80 pistols, and it has the accuracy advantage of having the barrel rigidly attached to the receiver assembly. Some side and under-lever makes are loaded by placing the projectile directly into the breech, while others are loaded by means of a ported tumbler which rotates up for loading and then pivots the projectile into barrel alignment.
One of the advantages of spring-piston air guns is their highly uniform shot-to-shot velocity. Just as with powder-burning guns, uniformity of velocity contributes to close grouping. On the other side of the ledger, however, are a couple of problems, inherent in spring-piston guns, which tend to cause accuracy problems. The first of these is the massive sear mechanism required to hold the powerful spring securely in the cocked position. A common by-product is a hard and creepy trigger pull. This is noticeable in inexpensive American-made BB guns, but quite a few expensive European air guns have equally poor trigger pulls. Apparently, the problem can be overcome only by complex, multilever trigger mechanisms which add to the price.
Page:
<< Previous 1 |
2 | 3 |
4 |
5 |
6 |
Next >>
