The problem is not the peep. It's the string. You can use all the gadgets mentioned above. Tube aligners, nock aligners, ets. I've been there and done that. What I found is that most generic or factory strings are the problem. They are made in an inferior manner or not twisted enough to make them stable.

Spend the money and get good aftermarket set. At least get the string. Have them installed properly, shoot about 50 shots to settle them in and then install your peep so it's pointing straight back. If everything was put on the bow right then the peep should not rotate at all. You might see about a 10 degree change in location during extreme temperature changes, but this should not keep you from seeing through it.

Now, what strings? You can spend $100 and get a set of Winner's Choice. There are others such as Vapor Trail, Prostrings, Wolfden, Stone Mountain, and many others. You can see a bunch listed in the classified on www.archerytalk.com. My personal recommendation is a guy right here on these forums by the name "GIBBLET". His real name is John Mraz and his strings are second to none, with customer service to match. If you have any problems or questions he'll be glad to help you. Give him a PM and see what happens.

I've had a set of his strings on my target bow for three years and nothing has moved since I set it up. Absolutely no peep rotation whatsoever.