No experience with the Impact.
BP is fine, easy to light, but may require wiping between shots, especially with modern projectiles that don't use lube. The REAL may help with that, but will have a pretty loopy trajectory for 150 yard shots. BH209 will give you good velocity and burns clean. A 10oz jug costs about $35 and will give you about 60 100gr equivalent (70gr by weight) shots. Uses regular or magnum 209 primers only, not special 777 primers.
For longer shots, sabots or the Hornady 350gr FPB are probably the way to go, but even though I shoot a scoped inline these days, I still regard it as a 100 yard proposition, as I don't have a way to verify accuracy and trajectory beyond that nor a place to hunt where that's likely to be a issue. Someone else can help you with that.
If you want a quick and easy recommendation to get started with and have a good chance of success, I'd say: get a jug of BH209, some Harvester Crush-Rib sabots, some 209s, and some good 250-300gr .45 caliber pistol bullets. Hornadys are good, but a little soft for velocities over 1600. Barnes are great, a little pricey, but tough, accurate and reliable. There are lots of possibilities, but you have to start somewhere. Browse back on this forum for more ideas. Good luck.
