Wrong…Please read the Iowa regs as stated on page 38 of the linked information:
https://www.iowadnr.gov/Portals/idnr/uploads/Hunting/huntingregs.pdf
RIFLES: Rifles firing straight wall or other cen-
terfire ammunition propelling an expanding-type
bullet with a maximum diameter of no less than
.350 of an inch and no larger than .500 of an inch
and with a published or calculated muzzle energy
of 500 foot pounds or higher is legal for hunting
deer during the youth and disabled hunting season
and first and second shotgun seasons.
This has nothing to do with general hunting regulations at all, it's for youth and disabled hunters.
Enjoy!