today's lucknow issue of DAINIK JAGRAN,stated that MARK IV,will be made available from the month of april,as iof has got the approval from the home ministry in the month of dec.2010,for its production and sale.
it also says that seeing the excitement among the customers both SAF and FGF have decided production on a larger scale.
about the specification,the article states that (according to the SAF sources),it is going to to have a longer barrel,which will give longer range,as compared to mark i,ii,and iii.
with improved butt for comfortable grip.

Tomorrow i will be attaching the scanned copy of the article.
regards,
happy and safe shooting....

Mariner.