My best time ever practicing for the Pyramid Air gunslinger event was just under 2 minutes and that was with my HW97. 16 shots with no misses practicing at home with actual metal silhouette targets chickens,pigs,turkeys and rams. I haven't practiced in a few years and timed myself the other day and i was consistently in the 2 1/2 minute range shooting 18 shots at paper,,,,figured a few extra shots for some misses,,,this was with a AA Prosport with a stiff cocking effort shooting 16ft lbs. In my opinion its not what gun you use but more how fast you can handle the pellets and get back on target. Of course the more you practice the better you get but id say if you can get it down to the 2 minute range with a springer than your doing pretty well. I constantly did things differently and timed myself what was the fastest way to do everything involved in the process,,,,every second counts.
Also it has been my experience that under levers are more accurate than break barrels for field target work. Look to see what the top springer HFT shooters are using and that will tell you alot.