Never had any luck with twist offs. If you over carbonate, which we all have done from time to time, there's a possibility the caps will blow off. The best way to get freebie bottles is from your local tavern. Or if you have a tavern, resturant or sandwitch shop in your area that sells and serves imports and speciality beers you can get pints and 22 ounce bottles. That's where all of mine came from.