514??? Love them but... this is not a new gun. I think they stopped making them in the 70's? Regardless, my first guess, since you have cleaned the crud out of the bolt... Those mil surplus with a bolt full of cosmoline... that is slow lock time... TIRED SPRING. You might still be able to get another from Remington. Brownells.com might have something in stock. Or you might get something with a little extra "ooomphhh!" from Wolfe or other supplier of springs. Following a thorough cleaning and inspection for burrs, that is where I would go next. luck.