I am wanting to make somewhat of a heavy sporter out of my remington 700 sporter weight rifle in 270 win, I want to retain the rifle as a 270win but gain about .5 to .75 #'s in the barrel, so a finished weight of the rifle would be 8-8.25 #'s I also want to keep the barrel 22" like the factory one that is on the gun. I am wondering if this would be a #3 or 4 contour, I am looking mainly at shilen barrels but I think their contours are pretty standard

I have a 20" number 7 that totals 8.5 with scope and synthetic stock. You may want the 5 1/2 contour in 22" which may be close to what you want.

Unless you want to or need to replace the barrel it would be easier and cheaper to add lead to the fore end and butt to achieve the desired weight. Just a thought.

I want the added weight for accuracy benefit, I figure the slightly heavier than factory barrel will likely make the barrel less finicky about different loads and aid in accuracy, so I guess what I am asking is how a #4 will compare to my 22" factory ADL barrel

All of the barrel makers (Douglas, Lilja, Krieger, PAC-NOR, etc.) list the weights of each contour they make. Just go to their websites and check "Contours" and it should provide you with the various weights.