Thanks for all the replies lads.

Just a bit more information from me as to why i want as flat as possible with centre fire rifle.
My license is up for re newel in march, over this five year period i have to date shot 796 foxes with the 223, this is over a lot of permission's protecting lambs, poultry and work for a game keeper.
I am averaging 28 night time hours every week, two/three time a week this involve's a round trip of just over 100 miles.
The 223 has served my well but because of the above i really need to have a maximum range rifle for when field condition's and my shot placement arn't perfect, im wanting to get out to around 300 yds without hold over, don't get me wrong, most of my shots are around the 150 yd mark, but there are quite a few time when the fox won't call in and it's not alway's possible to walk them down.
Some of these's foxes that have escaped through what every reason can be another ten or so outings before i get it, mean while live stock is being taken---------just trying to give myself maximum chance providing its safe to do so.

Dave (warbucks)