i've been using 12.0 to 12.5 grains of unique in one of my 30/06's for years. i have never used a filler. i've not had any miss-fires or squib firings in 20+ years of shooting it. i use a 160 grain lead bullet without a gas check. the rifle will shoot into 1/2" at 75 yrds. the only thing over the years that i have noticed is that the rifle will not shoot for crap without trimming alll of the cases to the same length. also i don't crimp the cases either, just bell them and load them as usual. if your worried about the case capacity though just use a mag primer, the extra flash of the primer will light anything.I've seen similar references in the past, Neo. Do you recall whether or not a filler is used to offset the greater case capacity?
Rich as for big cases and small powder charges the one thing you have to stay away from is light charges of slow burning powders. if you under charge a slow powder you could run into a case of pressure excursion. meaning that instead of the powder burning evenly the charge detonates. this will cause the pressure curve to spike exponentially on you and could ruin you day or your life for that matter. at the very least it could destroy a rifle that your holding very close to your face. as for lighting off to much fast burning powder at one time, you have to consider that the maximum chamber pressure your talking about with 12 gr's of unique is around 12-15k psi, in that big case. if your rifle has been made in the past 75 to 100 years you should be able to fire bunches of rounds at these pressures. if the load is to low you have to deal with the case not expanding enough to seal the chamber and you get blow back.