I'll agree with what a few others have told you. If a guy your size is really bothered by .270 recoil, something is amiss. It is probably improper technique mixed with a gun that may not fit you well. Rifles kick, but a .270 is pretty mild IMO. Get squared away with the help of someone who knows what they're talking about. I weigh 190, and I can shoot my '06 and 45/70 without recoil bothering me for say 25- 30 rounds. Getting shoved around wears on the average guy after that many shots, but it still isn't painfull (maybe sore the next day though).

Shotgun slugs do kick pretty hard, especially a 3.5" out of a single shot. But again, if you experience a "broken shoulder" kind of recoil, I suspect something is up with your technique. It is good that you asked for help early on, before any bad habits really become hard to break.

For range work, consider using a shooting pad to allow you to get more work in. In a big game hunting situation, you will barely notice recoil.