Accuracy sucks, Advice needed (update)

[kisfish]

I have a rem 700 bdl in 300 win mag. I can not get it to shoot  under a 5" group at 100 yards. Here is a little history on the gun. My dad bought it used I would guess 25-30 years ago. It would  shoot groups that you could put a quarter over at 100 pretty regular with factory ammo. About 10 years ago he gave me the gun and said it wouldn't hold a group any more. He said the gun got wet from the snow while hunting in Colorado. He took it apart cleaned and oiled everything. Dad said the barrel was not floated any longer.

 Fast forward to last year and I got it out and started messing with it. Sure enough the stock was a bit tight on the barrel. I couldn't slide a dollar between the stock and barrel on the left side. I took it all apart oiled reassembled and still tight. I very lightly sanded the left side of the stock and was able to get it loosened up.

 Back at the range with factory ammo and reloads it will not group. Left, right, up and down. No rhyme or reason as to how they are hitting on paper. It has a nice break installed from a gun smith and doesn't kick bad. Its not a flinch problem. I would bet dad put 200 rounds through it since he got it. I have put 35 or so down the pipe. I don't know how many from the previous owner. I am thinking of having the throat checked first. Then mount up a new scope to see if that's it. Then move on to a new stock after that. Any other ideas from you all? I have cleaned the heck out of it so I don't think fouling is the issue.
Thanks Ken 

[Branden]

I would make sure rings and bases are tight. If they are I would swap out the scope to one that is known to hold zero and test that. Those are free to do besides the ammo.

I had a good shooting rifle start shooting crappy. It ended up being a ring that cracked by the base.

Good luck

[davef]

Check all screws to to bottom. Make sure it's in the stock correctly. No binding or crooked. If that's not it then look at the scope. If still not it I'd bore scope it. Barrels probably fine but just rule it out. If the barrels not touching the stock I wouldn't throw money at a new stock unless you just wanted one. Rather have the old stock bedded.

[yorketransport]

Try a different scope on there. This sounds like a bad optic or mount.

[Biggerhammer]

I agree with trying a different scope.

[kisfish]

Thanks for all the reply's . It turned out the rings were junk. It looked like when it was put back together the base got a little tweeked when going on the back on the action. I ordered two sets on new rings and picked up a vortex from a member on here to start off with.
Slapped the new rings on and the same scope. I went to the range today and its holding nice tight groups again. Looks like I need a new gun for the extra stuff