Ovny - the short neck is of little or no consequence in loading the .300 Win Mag. I have never had ANY trouble with short neck cartridges.

As to factory ammo, the only factory ammo I have purchased in the last 40 years, has been a single box of 150gr. GMX Hornady ammo for my .308 Carbine. The ammo was on sale, 30% off, so I bought it, tried it - didn't like the accuracy, so saved money not having to buy a box of 50 bullets for re-loading, which cost twice as much as the ammo.

I think most of the 'bad press' on short necks comes from gun writers getting paid by the word, so they simply talk more- much of it nonsensical - quack, quack, quack.