More Chinook is not an option, so does M777 which are indeed light but reliability of gun barrel in mass firing is in question,
"KEEP IN MIND INDIAN ARMY USE 155MM IN BATTERIES NOT AS INDEPENDENT FIRE SUPPORT ASSET", exception can be certain cases during Kargil war but long forgotton now,
"People must observe Hardware but never forget training & tactics along user mindset !!",
M777 is not meant to be used in mass firing, Army is happy around upgraded M46 compare to M777s, Since they present practices was not failed and challenged against better ( Like Chinese ) the old habits will stay strong, ah Money was never an issue..
Adding: About Chinooks, MI26 were soon to be redeployed may be in 6 months or less..