300 Win Mag Accurate mags will work fine as the 7 PRC has a far shorter COAL than the 300 Win Mag.
Ive seen plenty of 300 PRCs run fine from the 300 Win Mag Accurate mags, so dont sweat the idea that the PRC is fatter. They use the same magnum sized bolt head.
FWIW, I run my 300 PRC from 300 RUM mags, but only because I want the extra COAL length for messing with reloads.