When shot through a high powered air rifle,over a 1,000 fps or so,just what type air rifle pellet will expand to the largest diameter when shot in game or a game like target???

You really need to test this for yourself as expansion is not the whole issue, nose shape & deformation characteristics will have as much to do with tissue disruption as the ultimate expansion does. l assume u r looking for maximum tissue disruption in ur target? This is usually achieved with the heaviest flat nosed projectile u can get, but penetration is compromised & a round nose will normally penetrate better. Spire points r less reliable but can expand well & give good penetration. You need to test for yourself as all rifles will differ, accuracy should be ur number one concern & penetration is number 2. As stated earlier the flat nose will give maximum tissue disruption & if the accuracy is good enough & the penetration is adequate then they will be the best game getter's.