.707 inch (12 bore)

When war broke out in August 1914 the Royal Naval Air Service was charged with the responsibility of defending Britain’s shores from air attack by Zeppelins. At that stage in the development of fighter aircraft offensive armament was limited to small arms and in an attempt to improve on the various rifle calibre weapons that had been tried, the Admiralty purchased a number of 12 bore double-barrelled shotguns from Messrs. Holland and Holland.

Two types were obtained, a standard smooth bore choked type and a partially rifled Paradox type. The guns were essentially similar, differing only in the type of barrel fitted.

The normal 12 bore choked version was known as the Holland Aero Gun and the first guns were delivered by Holland and Holland on 23rd November 1914.

The Aero Gun was designed to be fired with either buckshot or chain shot whilst the Paradox was to be used with the incendiary round, although the latter could also be used with the other cartridge types if necessary. Details of the special ammunition for these guns is given below.

The Paradox was designed to fire a rifled slug and had been popular for big game hunting at the end of the nineteenth century. It differed from the Aero Gun in that the last few inches of the barrels were rifled to impart spin to the projectile and improve accuracy.

Like the Aero Gun, the Paradox guns were fitted with a rear sight consisting of two folding leaves, one set for 50-100 yards and the other for a rather ambitious 150-200 yards.

Ammunition for the Holland and Holland guns was generally known by the normal title of 12 bore, but contemporary records also refer to it as “.707 inch” calibre.

Three types of load were introduced for Naval Service; Incendiary, Buckshot and Chain shot, all of which used a solid drawn brass case with the normal Holland and Holland commercial headstamp. It is believed the “Special Aero” cartridge referred to in the Holland and Holland records is the Chain Shot cartridge.

12 bore Chain Shot

"Cartridge Chain Shot 12 bore Mark I N" was approved to design CIW 2380 and shown retrospectively in Lists of Changes Paragraph 19675 dated September 1916.

Extended view of Chain Shot from Admiralty handbook C.B.1161.

12 bore Buckshot

The 12 bore incendiary cartridge was not shown in Lists of Changes, but had it followed the nomenclature of the chainshot cartridge

its title would have been "Cartridge Incendiary 12 bore Mark I N", but this is only conjecture. The title on the drawing however is "Holland Buckingham .707 Incendiary shell". As this title suggests, this was an early design by John Buckingham which is shown in the Admiralty handbook C.B. 1161 alongside early .303 inch and .45 inch incendiary bullet deigns. Essentially these differ from his later designs in that the phosphorus is expelled from a hole in the base of the bullet rather from weep holes in the side.

The case was solid drawn brass lined with brown paper and had a normal commercial headstamp of "Holland & Holland No.12 ELEY".

the load consisted of a lead slug complete with integral driving bands that was filled with yellow phosphorous. The base was closed by a lead plug, referred to in the official description as a nipple, with a central channel that is itself closed with a thin lead diaphragm. The whole was made airtight by pressing the nipple tightly into the body of the shell, sealing with Pettman cement and spinning the body over the end of the nipple.

On firing, the diaphragm was perforated by the ignition of the propellant charge and phosphorous escaped and was ignited by contact with the atmosphere. In addition to having an incendiary effect when it struck the target, the shell left a distinctive smoke trail in flight as the phosphorous burnt on contact with the air.

The propellant charge was about 35 grains of smokeless powder. with a single wad between it and the slug.

Drawing from Admiralty handbook C.B.1161