I am no expert, just reading up on FT at the moment but I don't see why you couldn't use one for the 20 ft lb and under hunter division. I am looking at the 2018 rules, I don't know if those are the latest. But I think it would work fine. You need a scope that is or can be set at 16X or under and a gun under 20 ft lbs. There are other rules but nothing I can think of that would disqualify a Marauder. I'm assuming in my response you are in the U. S. Rules are different in other countries - like you might be limited to 12 ft. lbs. Don't know if a 177 Marauder can be tuned that low but it probably can.