I've had 'em in 24" and 26" lengths. Current 7mm mag is a Ruger Number One with the 26" tube - I really like that rifle... Preferred load over the years is a 160 gr bullet at 3000 - 3100 fps, although I've used heavier and lighter as well.

With a high-velocity smallish bore magnum, a 24" barrel, or longer, just seems to make sense.

Regards, Guy