one day, you are fortunate indeed to have so many rifles that shoot 1/4 to 1/2 moa day in day out at those ranges. going to 1000 and 600 yd benchrest matches as well as 500m fly shoots, and looking at the wailing wall has presented not a lot of that kind of accuracy with guns built to benchrest standards with benchrest actions and barrels, and using solid benches and sophisticaed rests and rear bags. this with guys that specialize in these disciplines. they adjust loads for temperature and atmospheric conditions each day and during the day, and chase the rifling relationship to the bullet ogive 0.003 or less all the time. they use straightline dies and arbour presses. interestingly many of them only throw powder charges, although this is being supplanted by weighing more and more at longer ranges. fclass guys find it hard to guarantee 1/2 moa verticle, and sideways will always be bigger because even a couple of mph wind change, (undetectable) will move a bullet significantly. not only sideways, but up and down. such wind changes can also bend the light, making the target appear in a different place totally unnoticed. they clean every group in br, and then use a sighter target until the barrel settles again, usually 2 or 3 shots max. fclass guys cannot clean as often, as they have to shoot longer strings, and sometimes mark targets for other shooters. some fclass guys used to let cleaning go for 200 shots, but that has generally gone away now as guys have had accuracy go off. in your case statistics would suggest that the above is unnecessary, so you must go with what works for you. bruce.