While out shooting some 40 S&W recently, I noticed that some of the FMJ bullets were starting to set back in the case. Luckily, I found the problem before a ka-boom happened. I wouldn't want a series of problem rounds to cause someone to inadvertently (and unjustly) blame my G22 for the ka-boom. After some investigation, back home, testing ALL of my loaded 40 stuff, I found that all of the problem rounds would push back into the case with light, finger squeezing pressure. All of these were rounds loaded with PD 165gr FMJ, in the older Federal brass. No other bullet in that brass, would move, even under considerably more force. This only happened in what appears to be a much older version of that brand brass. The newer stuff has a different font/stamping and never had the same problem. All of the bullets were .400, just like the other brands on hand, and all of the brass was sized, seated and crimped on the same dies, Hornady. After a little more experimenting, I found that older R-P brass had the same problem...only with these bullets. But, these PD bullets would hold tight in all other brass that I tried. Blazer Brass,Winchester and S&B all worked very well. So, now I need to separate brass just to use with these 40 cal, PD bullets. I have 1000's of other PD bullets in other calibers and never had a problem with them. I am thinking about calling them to see if they had a bad batch some time ago that they caught later on, maybe a taper on the bearing surface or something. But any of the ones that I checked looked to be in spec. Weird, huh?