If it were me, I'd be somewhat leery of shooting a rifle cartridge like 270 WIN out of a short pistol barrel. Mind you, I've done it. It works. It's safe. It's just that you have all that powder to burn and such a short barrel to burn it in. The results I've had to date were that you end up with a lot of muzzle flash, and nothing to show for it in the way of velocity. In the dim light of early morning and late afternoon, that flash becomes blinding, as burning powder spews out of the barrel. Of course, once it's out of the barrel, that powder is contributing nothing to the downrange performance of the bullet. It also makes for a sizeable blast. One of the reasons I don't hunt with a pistol is that it forces me to wear muffs, and that detracts from my hunting experience. I like to hear what's coming.
My advice is that if you're not reloading and can cook a load using fast-burning powder, to stay away from high-capacity rifle cases and pistols. Having said that, I've seen good things out of a Contender in 30-30 WIN using factory loads, but there is considerably less powder in a 30-30 than in a 30-06 sized case like a 270 WIN. If you're into .277 as a bullet choice, go with the 7-30 Waters.