If you read the thread the OP is looking for advice on humane dispatch of fox in a cage,
All those recommending a 222 or .223 for the job please sit down!
CF for close quarters, urban dispatch is a disaster waiting to happen!
Personally I wouldnt want to use a 410 either, could make a hell of a mess of the cage and the spray could warrant a shower curtain.
An FAC air rifle "could" do it with the right pellet and power level but it is so close to the line on "humane" I wouldn't do it or recommend it.
If this is your business i.e. urban fox control then the FLO should have no problem with .22rf for "humane dispatch". only problem I see is the solid lead projectile, but some CB longs as opposed to standard subsonics would be silent and deadly at very close range and not have the power to ricochet.
for the cost and hassle of getting a FAC air rifle for rabbits you could get yourself a .22lr cheaper to buy, feed and maintain, better range, and would do both jobs.