Our backstop is rated for rifle rounds up to 30-6. We just dont allow them because of added risks and it is very loud to crack one off inside a little 4 foot wide booth. Also 25 yards with a 30-6 is pointless. Get the 357/38 unless the price and availability of ammo doesn't matter. If your only going to shoot it a couple times a month you won't notice a difference, but if we see you a couple times a week, feeding that Henry Big Boy could be an issue. Either 357 or 44 can be shot @ Calibers.
What bolt gun are you selling?