Gun and Shell Factory, Cossipore, Calcutta, is the mother unit of Indian Ordnance Factories under the Ordnance Factory Board, aptly known as the fourth arm of defence. The factory started its journey when the hallowed land at Cossipore was bought in the year 1801 and production activities started on March, 18, 1802. The construction of sheds under the guidance of Capt Prestron of Military Engineering Service at an estimated cost of Rs 20,000 included an eight-and-half feet high and 1435 feet long surrounding wall and 301 feet wide and 161 feet high tiled sheds along with the wall. There was one big shed of 50 X 40 X 20 feet at the centre for the saw yards. Some sheds were made of bamboo, dharma and jute twine. Machines were operated by bullocks and buffaloes. Thus started the functioning of Gun Carriage Agency, Cossipore in 1802.

After some initial expansion in 1804 and 1806, the work came to a halt in 1806. But after receiving some orders from King of Persia, the factory got back its life. In 1814, the Gun Carriage Agency was shifted to Allahabad and from there to Fatehgrah in 1816 as the Gun Carriage, because wood seasoned in Bengal was not suitable for the extreme climatic conditions of Northern India where East India Company was involved in wars. With the starting of Fatehgarh Agency, the importance of Cossipore Gun Carriage Agency was diminished and its existence ended at Cossipore in November 1829 when all the machines were shifted to Fatehgarh.

Cossipore had the strength of springing back to life again and again. The vacant space was utilised for
the much-needed expansion and renovation of the Gun Factory of Fort William which was under some criticism for high cost and bad quality. New plants were purchased from Europe as per suggestions of Capt G Hutchinson who had been inducted in 1822 in the newly created post of Superintendent and Director of the Foundry at Fort William.

The estimated cost of establishing the new brass foundry and a small iron factory was Rs 66,435 in 1829. The yard was renamed as Gun Foundry Factory in the year 1830. The construction work was supervised by Capt Hutchinson assisted by Lt T Renny. The construction was completed by the end of 1834 at a total cost of Rs 1,10,447.

The main attraction of the new complex was the 'Turning and Boring Room' constructed at the same site where was the big sawyer's shed during the period of Gun Carriage Agency. This hall was 1691 feet long, 50 feet wide and 40 feet high having a total area of 8,462 sq ft which was very near to the total area of 9100 sq ft of the new Birningham Town Hall, the biggest hall in entire Europe at that time. The construction of the roof was specially highlighted in the engineering circle. The Calcutta Review wrote, in 1845, that the construction was "one of the most complete and perfect to be seen in the country, erected some years back by Major Hutchinson of the Engineers after he had ransacked England and Europe for the best models. The bullock-driven machines were changed to steam-driven machinery.

The new foundry at Cossipore started functioning well and, besides casting of brass guns, it also took up manufacture of iron shot and shells. Its products were continued to receive appreciation from the Company's court. The credit went to the then Superintendent, Capt Archdale Wilson. During the revolt of 1857 when Indian sepoys turned against the British and sparked off a national rebellion, the then foundry factory was asked to double the production of guns in order to speedily replenish the British arsenal. The then Superintendent of the factory, Capt Broome said the Cossipore could produce 30 artillery guns a month instead of the regular 15 by running night shifts. But that was not finally undertaken in consideration of possible fall in quality. During 1858-59, Cossipore had a mini bullet plant.

Around 1855, breech-loading steel rifled guns had got its way to the British arsenal. During the period 1859- 1861, Capt Broome made several attempts to rifle the available smooth bore guns, but could not succeed. The Cossipore plant was not equipped enough at that time to undertake manufacturing of steel rifled guns. So, there was almost no work for Cossipore Foundry and there came suggestions for its closure. The mini-bullet factory was transferred to Ordnance Factory, Dum Dum. But Cossipore survived again.

The rifled guns, imported to India from England, required new elongated shells. It was decided that Cossipore would be utilised for manufacturing of the new shells. More land was purchased and a new workshop was constructed for shell processing. As there was no more processing of any gun at Cossipore at that time, the name ‘Gun Foundry’ was changed to ‘Foundry and Shell Factory’ in 1872.

Alongwith the manufacturing of new elongated shell, there was requirement of undertaking manufacturing of modern fuses and cartridges to match the newly introduced breech-loading guns. So more expansions took place in 1887 and 1890. In 1892, steel was for the first time cast in India at Cossipore by a Siemen’s Martin Open Hearth Plant. In 1896, a rolling mill was erected where- from large varieties of steel bars of different sections had been supplied to Railways, ship building industries, military engineering works and different ordnance factories. To meet the ever-increasing demands for steel in India, it was decided to shift the metallurgical units to Ishapore in 1903 as no further space for expansion was available at Cossipore.

In 1890, a shop was erected for the manufacture and repair of fittings of imported breech-loading guns. This had finally helped to undertake manufacture of quick-firing guns in 1905. With the return of the manufacturing of guns, the name of Cossipore unit got the present name of ‘Gun and Shell Factory’ in 1905. The Ishapore unit was also renamed from ‘Gun and Shell Factory’ to ‘Metal and Steel Factory’ in 1920, as a different unit.

Electricity was introduced in 1910 and new fuse and shell shops were erected between 1916 and 1920 as per Black’s Scheme of modernisation. The Ordnance Factory, Dum Dum was created and attached to Gun and Shell Factory from 1942 to 1966. In 1958, tractor project started here. This was the first ever attempt to manufacture tractor in public sector which was subsequently transferred to BEML. It had further extension during 1965-68.

As warfare changed over the years, so did Gun and Shell Factory. The
L-70 anti-aircraft guns capable of bringing down the fighters were one of the prestigious products. Its product-mix ranges from big barrel guns to small barrel pistols, different varieties of shells and fuses and civil trade items. With the large-scale modernisation, induction of state-of-the-art technologies and regeneration schemes, the factory will certainly survive its third century of existence. No factory elsewhere in India can match this record.