How many rounds do they typically get before velocity goes down and a recharge is required?
I’ve not seen any of them in person, other than the other day. A guy had one at the range and I loaned him my Garmin to check velocity. His started losing velocity before he got to ten rounds.
ETA: his was obviously not a high end rifle.
That depends on the size of the air reservoir, what pressure you fill it to, the caliber, the projectile weight, the velocity it’s tuned for, and somewhat on whether it’s regulated or not.
The standard Benjamin Marauder is a good benchmark for quality at a good price, and it has a robust aftermarket as well. For an average tune shooting 18gr .22 pellets at around 900fps, you should expect 40-50 shots from its 215cc air tube. Bump up to a bottle gun and you could easily make that 80+ shots per fill.
If you want to push the pellets faster, or want to push a heavier (higher BC) pellet or slug at the same or higher velocity, your air consumption goes up and thus shot count goes down. The 25.4gr pellets in .22 that are quite popular now will probably drop you back down to about 40-50 shots per fill if pushed at that same 900fps as the 18gr pellets.
These are rough numbers, of course. Lots of variables in tuning an air rifle, but that should get you started. Whatever the gentleman at the range was shooting either had a small reservoir, was pushing slugs at high velocity, or he was pushing pellets much faster than would generally be considered ideal.
