IMHO, even lug mating is such a minor part of the accuracy picture that I would look at other factors first. Things like bedding, loose screws, bad crown, so-so ammo, would be on my list of possibilities to be looked at.
What kind of rifle? What caliber? What sights are you using? What ammo are you using? How good a shot are you with other guns? Etc., etc.
FWIW, those are locking lugs. "Recoil lug" is the term usually used for a part of the receiver or a plate between barrel and receiver that fits down into a cutout in the stock to spread the recoil to the stock.
Jim