List of British Ordnance Terms - QF - Characteristics

Characteristics

In all types, the primer for the round was in the cartridge case base. The term QF in British use referred to the breech sealing mechanism, in which the brass cartridge case provided the gas seal. This allowed a sliding block, which can generally be operated faster than a BL screw mechanism, and is characteristic of small to medium artillery. Early QF guns offered the advantage over BL guns that no time was wasted in inserting vent tubes after loading, as the primer was built into the case, and sponging out of the chamber was not necessary between rounds. QF also removed the risk of back-flash. QF also, by rigidly fixing the position of the primer, igniter and cordite charge in the case relative to each other, improved the chances of successful firing compared to BL with its flexible bags.

By the early 20th century British doctrine held that QF ammunition, while allowing faster-operating breeches, had the disadvantage that ammunition is heavier and takes up more space, which was limited on warships. For guns larger than 6 inches it becomes impractical as the cartridge case becomes unwieldy for manual operation, and it does not allow charges to be loaded via multiple bags as BL does. Also, dealing with misfires was simpler with BL, as another tube could simply be tried. With QF the gunner had to wait a time and then open the breech, remove the faulty cartridge and reload. Already by 1900, modern BL breeches allowed the gunners to insert vent tubes while the gun was being loaded, obviating one of the previous QF advantages, and hence the Royal Navy abandoned the QF 6 inch gun and returned to BL 6 inch guns with the Mk VII.

Another potential disadvantage associated with QF came with the horizontal sliding block breech, as used with the QF 4.5 inch Howitzer. With the gun traversed at high elevation, the block could not be operated as it came into contact with the inside of the box carriage. Not all British QF guns in fact used sliding blocks - the QF 2.95 inch and QF 3.7 inch mountain guns and the QF 18 pounder used screw breeches. The thing to note is that their screw mechanism were much lighter and simpler than BL screw mechanisms and served merely to lock the cartridge in place.

It is worth noting that British artillery doctrine considered QF, even separate-loading, as unsuited for guns over 5 inches following its experience with the QF 6 inch in the 1890s, while European militaries such as Germany continued to use separate QF with sliding-block breeches for large guns up to 15 inches, with larger German guns loading part of the propellant charge in cloth bags followed by the main charge in the metal cartridge case.

In colloquial use, Quick Firing is artillery having attributes like recoil buffers and quick shell loading characteristics, introduced in the late 19th century.

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