Re: best factory ammo
I'd agree with Chris. best ammo is what your rifle shoots best with.
I personaly prefer Black Hills, Hornady, Lapua and Norma.
Its isn't a Gods given that any particular rifle will shoot best with the most expensive ammo. Ask Elwood about his Sako and the cheapest ammo he could buy, shot best, like wise ive a 7x57 on a mauser action that just loves Sellor & belliot, cheap as chips ammo.
I habe personaly found no difference in ammo from lot to lot number whilst using Hornady. Lapua, Black Hills or Norma. Hirtenberger was good (we used Hirtenberger sniper ammo when i was playing with Brit Army sniper rifles a few year back it was good,but its hard to get these days)I can't say the same for any other ammo ive treid, be it federal, winchester, RWS,remington, and a shed load of other stuff.
I always thought it a shame that ammo isn't available in test boxes of 10 rds, you should be able to tell within 2x 5 rd groups wether the ammo shows promise or not.