The old Arms Act of 1878 did provide for certain firearms to be prohibited.However,I have so far not come across any list of prohibited firearms issued under it.The Arms Act of 1887 imposed sever restrictions on the import of firearms and ammunition.However,import of firearms by individuals for their own personal use was allowed(Section 6 of the Arms Act, 1878)the catch being that the person so importing arms and/or ammunition should be "lawfully entitled to possess such arms or ammunition".Indians were generally denied a license.Only those who were considered to be loyal to the then dispensation were able to procure one.The white settlers/civil servants were exempted from the provisions of the Arms Act.So were the Indian Princes.They could import any firearm that they so wished provided that it was in a "reasonable quantity".

So any prohibition on the import of a specific caliber firearm or ammunition would not have applied to those exempted under the Arms Act.I have seen a large enough number of 303 rifles including some Lee Speeds and a WR double rifle, that would indicate that the private ownership of 303 rifles was not unusual.

Re. the export of firearms from India,after independence,many of the dealers importing arms and ammunition into India shut shop.Some of the old names existed but operated in local hands.The Indian govt. in a misguided attempt to encourage local manufacture and to save scarce foreign exchange,began to discourage import of goods,including arms and ammunition.Dealers were not granted licenses to import arms and ammunition.Ammunition for many of the firearms became hard if not impossible to find.Thus coupled with the reduced financial condition of many of the owner of these fine guns,lead many to sell them to dealers who exported them in bulk.The abolition of the privy purses granted to the Indian Rajas meant that many were reduced to selling anything that could be sold.The special status accorded to them was also withdrawn including the exemption from the Arms Act.This made it extremely inconvenient for them to hold on to a large no. of firearms.Many kept the best ones with themselves and the rest were sold with the bulk being bought by dealers for export as the prices in India were lower than what people were willing to pay abroad.

Re. export of firearms,antiques, firearms of the type/caliber used by the armed forces and firearms for which import of ammunition is allowed can't be exported.