Indians For Guns

To my knowledge validity period of Arm Licence for
1) NPB Gun/Rifle is 3 years or one has to get licence renewed every three years
2) NPB Revolver/Pistol is 2 years or one has to get licence renewed every two years

3) 2 or 3 NPB weapons including at least 1 handgun is 2 years or licence is renewed every two years

Now for example: Is licence is initially for gun, say renewed on 1 April 2009 and valid upto 31 March 2012. Later on 11 Dec 2010 revolver as additional weapon is sanctioned and Purchase period of six months is sanctioned. Weapon is purchased within purchase period and entered in licence. It is understood that this licence will be renewed every two years, but from when?
Will the validity date of such licence be changed to one year from date of issue of additional weapon (i.e. 10 Dec 2011 in this case)or not?
Here in Maharashtra I have seen that fresh licence for Handgun is renewable at 1 year from the date of issue and then renewable every 2 years.

Gurus - Your opinion and advice on this. Any reference to such a thing in Arms Act or Arm Rules?

ARMS ACT says 3 years.
however there are exceptions where 1 year can be given.

normally its 3 years.