rugerfan,
I've seen two action screw sequences for the M77 - both agree - front first and very snug, as this angled screw pulls the action into the bedding of the stock. Ruger recommends then alternating the tightening of the rear and middle screws until they are both evenly "snug". The other way I have seen, and I think it makes sense, is to tighten front first (very snug), rear 'snug" next, and the middle just barely snug, and never more than that. I have some torque values for my model 70's and a torque screw driver I use for them, but I have never seen numbers for M77's. I think this factor is significant with all non-pillar bedded rifles, soI believe I will call Ruger and try to get a number from them. "Snug" and "very snug", etc. can vary a lot between gun owners due to interpretation. You probably know, but I'll say it anyway, don't tighten like the lug nuts on your car. Screws are powerful and can distort things, and they need to hold a well bedded action tightly in place - but if the action is not fitting firmly against a good bed, then the screws won't make up for it no matter how tight, and between the three (screws) of them they can distort the barreled action as it sits in the stock.
As far as the tip pressure on the stock, the bad part is that this is something that can either be good, or bad. The good part is that it is easily remedied. I believe about 10# pressure is a fair range to work around. Tht's not a whole lot, just firm. Something you can do with your fingers by gently lifting the barrel away from the stock at the end and seeing how the business card, (or cards) slide in there. A matchbook cover is thicker. If, under no help from you, it's pretty firmly gripped there, you probably have adequate tip pressure. Shoot it like that and see if there are are any changes. Again - go lightly and slowly. You can always remove the tip ridge with sandpaper, and you can always restore it with some bedding compund and trim with sandpaper.
Probably more often, the answer is to free float the barrel. Sorry, I wan't more clear - the magic marker is to wrap the sandpaper around. Of course any round cylindrical object 3/4" or so, will do. You want the barrel to be consistently free of (variable) stock contact under all conditions. Again, take your time, check often with something to gauge the clearance you are creating, and re-seal against moisture when done.
I hope this helps - I am not a gunsmith, so take it all as well-meaning opinion. Go slow and easy with everything.
I agree with you on your accuracy expectations. Rugers often need a little tweaking like we are talking about, and the older ones (without the new trigger I have heard about) usually benefit from some trigger work or replacement, but I personally believe Rugers are often way underestimated in their accuracy. I am more of a hunter and casual shooter, but my Rugers shoot as well as I work at my shooting, and I have several friends who really take their riflery seriously and they get fantatstic results with their Rugers. I think they make pretty fine barrels now, and although 1 1/2" is very good hunting accuracy - I think yours will do better. The other thing I would repeat - they have a very good customer service reputation and they do want you to have an accurate rifle.