I used to use 150 till I got a rifle that didn't like em. For some reason or another my Ruger just doesn't group 150 grain bullets like you would want. It loves 165 grain bullets though, so that's what I use.
Now while we're on the subject. I loaded some 165 gr. Sierra boat tailed spitzers a few seasons back and all the family 06 rifles (3) loved em, but I didn't like what we saw in the field. I had some really blow up in whitetails. It didn't cost us any deer, all were killed, but it was mass fragments in a couple of good bucks. Seems they are more for targets than for game.
I switched to Hornady interlocks last season, but one of my brothers 06's didn't like those.
I just bought a box of Sierra Gamekings today. We should be back in business, and they are supposed to hang together on whitetails.
Time will tell, I'll be loading up a batch, and we'll be at the range and then to the deer field in the next few weeks. I sure hope the gamekings are the ticket, it's nice to only load one recipe for everyone.