I am experiencing loose primer pockets on some of my cases.They have been reloaded about 7-8 times and are magnum cases.I am loading both a .270 and 7mm Weatherby,using an RCBS primer pocket cleaner on both also.I have not had no problems with the .270,but some 7mm cases have little or no resistance when seating the primers.Is this a cause of some excessive pressure on some of my 7mm loads,or something to do about how much force is applied to clean the pockets.I kind of rule the latter out seeing as how I do the same for both calibers.I have not exceeded manufacturers recommended loads and not showed any excessive pressure while visually checking cases and primers.What is normally the cause for loosened primer pockets?

Loose primer pockets are almost always indications of maximum loads. Not much you can do to loosen them up with the run of the mill pocket uniformers. You're probably at the maximum, or slightly over on your loads. Only way to cure that is to either back off on your loads or be prepared to buy new brass after 7 or 8 reloads. That's not actually too bad. I'd be comfortable with it.

7 or 8 reloads. Your primer pockets are gettin' kinda tired. Instead of pitching the whole lot, as you prime, mark an x with a magic marker on the loose ones and pitch them after the next shot. If they are really sloppy, pour a little 3 in 1 oil down the case, mash the mouth closed with a pair of pliars (so they can't be re-used) and pitch them before the last shot. I'd say that was pretty good for magmum cases however.