It won't work, without some significant accommodations.
First, the cases aren't that different, and working pressures of the round are about the same, so the case web isn't a serious consideration. One advantage may be that most Mag cases have small pistol primer pockets.
However, cutting brass defies their design. Case walls, compared to the case mouth, are thicker and usually more brittle (not annealed, if the mouths are routinely annealed). This causes a problem when fitting bullets. The thicker case wall will either have to be reamed to accommodate the bullet, and maintain bullet diameter and seated [new] case mouth outside diameter. Unless you do something about it, they won't fit into the chambers. It is just not worth it under normal conditions. If I had no other source of brass, I might be inclined to make it work, some way.
Life is tough. It's tougher if you're stupid. -- The Duke