I shoot a lot of Sambar being local to the area. I wouldn't worry about the gun size I shoot all mine with a 243. they are big but don't have the fistyness of a red and seem to give up easy most of the time with a well place shot anyway.
They are sneky krafty buggers and for there size can hind behind a blade of grass. They will some times drop to the ground if spooked and slowly crawl away so watch that!
They are dumb as shit under a spot light but clever during the day.
Move quietly and slow as they are very onto it. I find where I live they seem to be very nocturnal and during the day I find them in bushy fringes and shrubby patches just in the sunlight enough to get warm but not be seen.
Not sure if this helps much
Good luck and I hope you like sausages because they are shit eating
Bookmarks