Smooth bores may be a hair faster, but I'll trade a little speed for far-improved accuracy any day. You can modify your pump piston to have a flat-top and- after strengthening the pump arm- get every bit of speed back.I have one of the $20 all-plastic 760 pumpers that-once I swapped in the M4-177 barrel- produced startling results- like sub-dime groups at 20 yards. The main problem I have with that gun now is that it's too light And as cheap as the MK4-177 barrels are, you can get a couple and play around with various lengths to see if there's a sweet spot for a pumper carbine.