It would be interesting to examine the true nature of the agneya-astras. Kautalya describes agni-bana, and mentions three recipes - agni-dharana, ksepyo-agni-yoga, and visvasaghati. Visvasaghati was composed of 'the powder of all the metals as red as fire or the mixture of the powder of kumbhi, lead, zinc, mixed with the charcoal and with oil wax and turpentine.' From the nature of the ingredients of the different compositions it would appear that they were highly inflammable and could not be easily extinguished.
A recent writer remarks: 'The Visvasaghati-agni-yoga was virtually a bomb which burst and the fragments of metals were scattered in all directions. The agni-bana was the fore-runner of a gun-shot.....
Sir A. M. Eliot tells us that the Arabs learnt the manufacture of gunpowder from India, and that before their Indian connection they had used arrows of naptha. It is also argued that though Persia possessed saltpetre in abundance, the original home of gunpowder was India. It is said that the Turkish word top and the Persian tupang or tufang are derived from the Sanskrit word dhupa. The dhupa of the Agni Purana means a rocket, perhaps a corruption of the Kautaliyan term natadipika.
(source: Fire-Arms in Ancient India - By Jogesh Chandra Ray I.H.Q. viii. p. 586-88).
Heinrich Brunnhofer (1841-1917), German Indologist, also believed that the ancient Aryans of India knew about gunpowder.
(source: German Indologists: Biographies of Scholars in Indian Studies writing in German - By Valentine Stache-Rosen. p.92).
Gustav Oppert (1836-1908) born in Hamburg, Germany, he taught Sanskrit and comparative linguistics at the Presidency College, Madras for 21 years. He was the Telugu translator to the Government and Curator, Government Oriental Manuscript Library. Translated Sukraniti, statecraft by an unknown author.
He attempted to prove that ancient Indians knew firearms.
(source: German Indologists: Biographies of Scholars in Indian Studies writing in German - By Valentine Stache-Rosen. p.81).
(For more refer to article by G R Josyer - India: The Home of Gunpowder and Firearms).
In his work, Political Maxims of the Ancient Hindus, he says, that ancient India was the original home of gunpowder and fire-arms. It is probable that the word Sataghni referred to in the Sundara Kanda of the Ramayana refers to cannon.
(source: Hindu Culture and The Modern Age - By Dewan Bahadur K.S. Ramaswami Shastri - Annamalai University 1956 p. 127).
The word astra in the Sukraniti is interpreted by Dr. Gustav Oppert as a bow. The term astra means a missile, anything which is discharged. Agneya astra means a fiery arm as distinguished from a firearm.
Dr. Oppert refers to half a dozen temples in South India to prove the use of fire-arms in ancient India. The Palni temple in the Madura District contains on the outer portion in an ancient stone mantapa scenes of carved figures of soldiers carrying in their hands small fire-arms, apparently the small-sized guns mentioned in the Sukranitisara. Again in the Sarnagapani temple at Kumbakonam in the front gate of the fifth story from the top is the figure of a king sitting in a chariot drawn by horses and surrounded by a number of soldiers. Before this chariot march two sepoys with pistols in their hands. In the Nurrukkal mantapam of the Conjeevaram temple is a pillar on the north side of the mandapa. Here is a relief vividly representing a flight between two bodies of soldiers. Mounted horsemen are also seen. The foot-soldier is shown aiming his fire-arm against the enemy. Such things are also noted in the Tanjore temple and the temple at Perur, in the Coimbatore District. In the latter there is an actual representation of a soldier loading a musket.
The Borobudar in Java where Indian tradition is copied wholesale. They are ascribed roughly to the period 750-850 A.D. There is a striking relief series PL. I, fig. 5, (1605) representing a battle in which two others are seen on each side, one wearing a curved sword in the right hand and a long shield, and the other a mace and a round shield resembling a wheel, all apparently made of iron. The story of the Ramayana is also given as in the Tadpatri temple from Rama's going to the forest down to the killing of Ravana. There is also a wonderful sculpture of an ancient Hindu ship.
(source: Suvarnadvipa - By R.C. Majumdar. pp 194-5).
Medhatithi remarks thus "while fighting his enemies in battle, he shall not strike with concealed weapons nor with arrows that are poisoned or barbed on with flaming shafts."
Sukraniti while referring to fire-arms, (agneyastras) says that before any war, the duty of the minister of war is to check up the total stock of gunpowder in the arsenal. Small guns is referred as tupak by Canda Baradayi. The installation of yantras (engines of war) inside the walls of the forts referred to by Manasollasa and the reference of Sataghni (killer of hundreds of men) pressed into service for the protection of the forts by Samaranganasutradhara clearly reveals the frequent use of fire arms in the battle-field.
(source: India Through The Ages: History, Art Culture and Religion - By G. Kuppuram p. 512-513).
Lord Rama with his bow defeats Ravana in the gold city of Lanka
In the light of the above remarks we can trace the evolution of fire-arms in the ancient India. There is evidence to show that agni (fire) was praised for vanquishing an enemy. The Arthava Veda shows the employment of fire-arms with lead shots. The Aitareya Brahmana describes an arrow with fire at its tip. In the Mahabharata and Ramayana, the employment of agnyastras is frequently mentioned, and this deserves careful examination in the light of other important terms like ayah, kanapa and tula-guda.
The agnicurna or gunpowder was composed of 4 to 6 parts of saltpetre, one part of sulphur, and one part of charcoal of arka, sruhi and other trees burnt in a pit and reduced to powder. Here is certain evidence of the ancient rockets giving place to actual guns in warfare. From the description of the composition of gunpowder, the composition of the Sukraniti can be dated at the pre-Gupta age.
(source: War in Ancient India - By V. R. Ramachandra Dikshitar 1944. p. 103 -105).