FUNCTION DEFINITION CONTEXT

Lands And Grooves

In order that a projectile obtains the necessary spin when fired so as to develop a stable, stagger-free flight path, “spiral-shaped” indentations – actually referred to as helix-shaped – are worked into the interior of a rifled barrel. These are called lands and grooves – the grooves are the slots; accordingly, the lands are the projecting areas between the grooves. The internal diameter of a barrel can be indicated as a groove diameter (marking B) or groove calibre or as a land diameter (marking A) or land calibre. The groove diameter designates the distance between two grooves located opposite to each other; the land diameter indicates the distance between to lands located opposite to each other. Hence, the groove diameter is always greater than the land diameter.

Designations

The diameter of the projectile – which is often echoed by the calibre –mostly corresponds to the groove diameter. When the gun is fired, the projectile is slightly squeezed through the barrel and thus receives a characteristic cinch mark pattern, allowing it to be attributed to the corresponding barrel.

Fingerprints

Since hand sweat has a pH value of between 4.7 and 5.75 and is thus slightly acidic, it can etch fingerprints into metallic surfaces, which is also referred to as fingerprint corrosion. Even so-called “stainless” steel can be prone to this form of etching if the metal is not correspondingly protected – as “stainless” or “rustless” steel is actually better described as “rust-resistant”, since it, too, is susceptible to rust under certain conditions. Therefore, in the area of gun care in particular it is recommended to protect the metallic parts of the gun in order to prevent this form of corrosion.

However, a distinction should be made here between alkaline gun oils, such as Ballistol Universal Oil, which actually chemically neutralizes this hand sweat, and other products that merely dilute the hand sweat in hopes of making hands sweat less adverse. Although a few products advertise themselves with statements such as “neutralizes hand sweat”, they are not chemically capable of duing so, since they are not alkaline oils but rather neutral oils (e.g. Brunox, SchleTek, FlunaTec).

Projectile Deposits

To enable the projectiles to adapt to the barrel and absorb the spin, as well as not to damage the barrel, they are made using soft metals such as soft iron, bronze (softer than brass), brass, copper, zinc or lead and have a suitable coating. Therefore, when a gun is fired, metal residues of the softer metal of the projectile remain in the barrel. These are designated as projectile deposits.

SMOOTH SHOOTING AND ZEROING-IN

Both smooth shooting and zeroing are actually completely normal things. However, unfortunately they are often neglected – even though both are sometimes very important. Although so-called smooth shooting is not absolutely necessary, it is beneficial later when cleaning the barrel. This is because the surface in the barrel interior is slightly rough due to the type of production. This is more pronounced with industrially produced barrels than for example with high-quality match barrels. This roughness can be reduced through smooth shooting. The smoother the barrel is, the fewer opportunities there are for dirt adhesion and the easier it will be to clean the barrel later. With jacketed projectiles in particular, smooth shooting is profitable preparatory work; if other ammunition, such as .22 LFB (pure greased lead projectiles), is selected, it is not necessary.

Expert tip – competition

In competitions, marksmen often have only a limited number of test shots, sometimes none at all. Therefore, in order to avoid nasty surprises in competitions, marksmen should be sure to fire 5–10 test shots at their home firing range after the cleaning and/or before competitions.

To shoot a new barrel smooth, the barrel is chemically cleaned before the first shot. Residues from production, official fire and zeroing are thus removed. Robla Solo MIL Barrel Cleaner is outstanding for this. After this cleaning step, the first shot can be fired, after which the barrel is immediately cleaned again – a piece of felt moistened or soaked with Robla Solo MIL is completely sufficient for this. This procedure, shot and subsequent cleaning is repeated 5 times.

2 shots are now fired and the barrel is again chemically cleaned with a moistened or soaked piece of felt. This step, too, is repeated 5 times. In the next step, the barrel is cleaned after 5 shots, then after 10 shots. To make completely sure, a further step with 15 shots can be performed. Then at the latest, the new barrel is optimally shot smooth and can be cleaned more easily in future.

Whether it is necessary to zero in the gun or perform a test shot after cleaning depends on a wide variety of factors; however, the following applies: whenever the gunsight was removed for the cleaning, it should be zeroed in. Whenever the user has the feeling that the point of impact has changed, a test shot should be performed.