The rule of thumb that I remember hearing when I was having similar problems w/ a .220 Swift w/ a longish throat was 1/2 caliber, or in the case of a .224 cal. gun, about half that, or 0.112 inch. Not much, but it should be enough to keep things together.
Unless the gun is shooting horridly, I wouldn't worry about it. My .223 Rem bolt rifle shoots its best usually w/ the bullet seated back to magazine length, rather than near the rifling. Similarly, my .308 Win bolt rifle (recent production Remington 700VS) has 175gr SMKs (not a small/short bullet) jumping 155 thou to the rifling and will still shoot bug holes if I'm up to it. Seating the 175gr SMK (or a custom 185gr VLD that I have a few hundred left) out to the rifling really doesn't gain me much, if anything, noticeable on paper at any distance. So, again, if the gun shoots OK seated mag length, don't sweat it.
HTH,
Monte