Rifled bore weapons

Here primers and igniters are separate elements and not in one piece as for igniting proplnts in gun howitzer cannons, and in recoilless rifles. The weapons known as 60-mm Mortar Cannons M2 M19 arid 81-mm Mortar Cannons Ml M29 are smooth-bore. 

Little David . The latter weapon used a shell with pre-engraved band(Ref 12,pp 172-3)- As examples of smooth-bore breech-loaders may be cited the 2-in Mortar of Brit design installed on some US tanks used during WWII and the 75mm Infantry Assault Mortar, M1923. As an example of rifled-bore breech-loaders may be cited the 12-in Seacoast Mortar, Model 1890, which is now obsolete(Refs 20 21)... 

Small arms may be taken to mean weapons with a bore of less than 2-5 cm, whether the barrel is smooth or rifled. Compared with larger weapons, they have light bullets or shot and have relatively short barrels. Propellants used must therefore be fast burning and have small web thickness. The factors which determine design of powder depend also on the individual characteristics of the weapons. 

Accdg to Maj Hobart (Ref 3)> die ides of fin stabilization is much older than spin stabilization. This is because the earliest weapons were smooth-bore and they could use finned projs, while spin projectiles required rifled weapons which were notin-vented until about 1500. The earliest fin-stabilized projectile was an arrow and then fireworks projs, which could be called rockets. The earliest projs fired from smooth-bore barrels of small arms or cannons were like balls and they did not have any stabilizing attachments. However, accdg to the description given in Milimet Manuscript of 1326, now in Christchurch, Oxford, the earliest cannon, known as pot de feu (fire pot) was fin-stabilized (See also Voi 2 of Encycl, p C26fL)... 

The twist is almost universally constant in pitch, although older weapons with an increasing twist may be encountered occasionally. In the Latter case — provided the rifling continues to grip the envelope thruout the bullet travel in the bore — the final angle of twist decides the rate of rotation... 

Groove Diameter of a rifled weapon is measured from the bottom of one groove to the bottom of that opposite or, in case an odd number of these are employed, calculated as equalizing the diam of the bore (See "Bore Diameter in Vol 2 of Encycl, p B248-R) plus twice the depth of one groove, since in this instance these are so distributed that no one ever directly faces another Ref Hayes (1938), 194... 

Caliber is the diameter of the bore measured between opposite lands of a rifled small arm or an artillery weapon. The lands of a weapon are the raised portions of the rifling in a bore, and the spaces betw the lands are called grooves... 

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