if you want to duplicate the 45 acp in the 45 colt you just need to drop the bullet weight and load it light.
i don't know how much lighter you can go than 14-K in pressure, or how much less recoil you need than a 45 colt.
but there's tons of options out there to go even lower.
how about a 165gr. bullet from a 45 colt case moseying along at about 700 fps.
that puts the recoil level lower than a 38 special in the heavier gun.
if you want less than that, crossman makes a pretty decent bb gun.
i don't know how much lighter you can go than 14-K in pressure, or how much less recoil you need than a 45 colt.
but there's tons of options out there to go even lower.
how about a 165gr. bullet from a 45 colt case moseying along at about 700 fps.
that puts the recoil level lower than a 38 special in the heavier gun.
if you want less than that, crossman makes a pretty decent bb gun.