Get your wife the mossberg in .270 and let her shoot the recoil management ammunition from Remington. This way she will have a little better performance than the .243 with a little less recoil and still have the possibility to jump up to full loads if she wants to hunt elk.
Brandon
I don't think so, neither does Remington. This is the data fron their web site.
Velocity (ft/sec)
Cartridge Type Bullet Muzzle 100 200 300 400 500
(.243 Win) Remington® Express® 100 PSP CL 2960 2697 2449 2215 1993 1786
(270 Win) Remington® Managed Recoil® 115 PSP CL 2710 2412 2133 1873 1636 1425
Energy (ft-lbs)
Cartridge Type Bullet Muzzle 100 200 300 400 500
(.243 Win) Remington® Express® 100 PSP CL 1945 1615 1332 1089 882 708
(270 Win) Remington® Managed Recoil® 115 PSP CL 1875 1485 1161 896 683 519
Long-Range Trajectory
Cartridge Type Bullet 100 150 200 250 300 400 500
Remington® Express® 100 PSP CL 1.6 1.5 zero -2.9 -7.5 -22.1 -45.4
Remington® Managed Recoil® 115 PSP CL 1.0 zero -2.7 -7.4 -14.2 -35.6 -70.1
The trajectory figures favor the 243 even more. If you're going to use the 270 then use regular loads cause these don't come close toe the 243, plus the 270 will be a longer rifle, heavier, and most likely more awkward to handle cause of a longer action. I have a 243 and 30-06 and the 243 is much quicker to shoulder. Both ar Savage 110 rifles, so it is a direct comparison.