I asked the same question a few months back and got some nice replies. Ended up buying Mil-Comm TW25B and giving it a try. Probably the best lubricant I've ever owned. Only problem is the lube is so good is creates a synthetic film that takes up too much space in my tight tolerance Defiance Deviant’s.
After cleaning the bolt and inside of the action I discovered it still leaves a film. So, I’m applying the TW25B to the bolt then wiping it off with a towel to hopefully keep it from rusting, then applying some Frog Lube to make the action run smooth.
Shot a match last Saturday and had no issues but by day’s end the bolt was getting a little tight so dustier conditions would have required cleaning the bolt during the match. I love my two Defiance Deviant’s, especially the M16 extractor, but mine are really too tight for PRS style matches IMO.