Okay, so what i did was this: when i was working up a load for 300 wby i numbered all the cases from one to eight, with eight being the hottest load i tried. I got through them all without noticing immediate signs of pressure, except the fact that the last ones kicked very slightly harder than i expected them to. The problem i'm having now is that the cases marked seven and eight have slightly expanded at the belt, maybe by about 5 thousandths of an inch. But its enough to make them hard to put into the shellholder of my lee primer tool. Also the primers seat easy. They arent loose and i can't shake them at all by whacking the case on a table. The load i actually decided on using is on the low side but what i'm curious about is, are these cases still safe to use? oh and on a side note, if i switch from flat base bullets to boat tails of the same type will this raise my pressures significantly since they are longer?
thanks for any help you can muster.

If all cases except those of the highest loadings will seat easily into the shell holder, then those two are telling you the pressure ceiling is being bumped. Also, there should be a decided bit of resistance to seating the primers. That's why a lot of folks elect to use a hand priming tool - so they can "feel" the primer seating operation and detect any loosening of the pockets. Yes, it would be best for safety sake to discard the brass that has loose primer pockets and have swelled bases.

Unless you're planning on long range shooting, the benefits of using boattail bullets over flat base is an iffy proposition. Flat bases are going to give the better seal and, as you say, aren't as long and don't crowd the case capacity as much. Conversely, BT's are easier to seat due to the bevel. I've always found for normal range shooting (out to 350 yds) the FB's work just fine.

Toss 'em. Brass is cheaper than fingers.

I'd *highly* recommend getting a chronograph. For less than a hundred bucks, you can have a much better idea what your loads are running.

Glad you are putting safety first!