I usually keep the magnification on my scope at 16x, although for those REALLY long shots, I turn it up all the way (24x). while not necesary it is very usefull. Look through a scope at that high magnification and you can see just how much your crosshairs are moving. What appears steady at 4x, can be moving like crazy at 16x. So if you get them steady at such a high magnification, you are minutley ajusting the aim of you rifle untill you can get it exactly were you want it. I have never used a benchrest in my life when shooting at a range. I allways use an improvised rest like I would find in the woods. my knee, a jacket on a table, the crotch of a tree, a stump or log, or even my hand pressed against the side of a tree with the rifle resting between the thumb ant tme index finger. they all work great although nothing I've used beats my dad's brown jacket from Tractor Supply balled up on a table or the hood of a truck. portable, very steady, and it lets you track targets as they walk across your feild of veiw. We use it to sight in and we use it in the woods. As for the .223 being a varmit cartyrige, I don't know how deer are were you live but down here, they're like fairly large great Danes