XMarine,
Welcome to Graybeard Outdoors and the new Medium Bore Rifles forum. Tell your friends about us. As to your question the lightest weight bullet that I know of being factory loaded for the .270 WSM is a 130 gr., which in my opinion is too heavy for varmint use. As far as reloading you can get bullets for varmint use in .277 down to the 110 gr. Hornady V-MAX. the V-MAX is a very good bullet for varmints. I use them and recommend them. Lawdog