I load .38 Spl., .44 Spl., .40 S&W, .45 ACP and 9mm on a Dillon XL-650. The only caliber I have trouble with is the 9mm. Everything else works fine with boring regularity.
The 9mm problems come in two versions. First, if the crimp die is set too tight and I am using plated bullets, I get a little ring swaged on the bullet just forward of the case mouth. This looks like a very small SWC shoulder. It can cause the cartridge to fail to completely enter the chamber and jam the weapon. This does not occur with milspec FMJ bullets because their jackets are thicker and hard enough to resist the tendency to swage that ring on them.
Second, a certain percentage of the loaded round have a bulge or swell on them near the head of the case, just forward of the case web. This causes a hard jam when the round attempts to enter the chamber. This bulge could be the result of bullets not being straight when seated, or possibly because the brass does not enter the sizing die far enough. I use RCBS dies in my Dillon and the sizing die is quite short and has to be scewed down so far that it is almost impossible to use the lock ring on the die.
I use Dillon dies for the other calibers and am going to get a set in 9mm to see if it eliminates the problem. That 9mm case is short and tapered and apparently has a Teutonic temper when you try to reload it.
Another possible cause could be if the shell plate lock screw loosens and allows the shell plate to wobble, then the case might not fully enter the sizing die (and could possibly enter the seater a bit crooked).
To prevent problems, I follow the advice above and use my barrel as a cartridge gauge. It takes some time to do, but it's not a big problem if you do it while watching TV. If a cartridge doesn't easily drop in the chamber with a "thunk" or if it doesn't fall out freely, I do not box it up or load it into a magazine. Those that enter the chamber fully but are a bit "sticky" go in the "doubtful" pile...I shoot them up single shot, chambering them by hand, to practice quick target acquisition firing one shot at a time. If the rounds give more trouble than that, or refuse to enter the chamber at all, they go in the "reject" pile, to be dealt with creatively at a later date. I plan to get a Lee FCD to try to rehabilitate them...otherwise I will break them down at some point.
98% of the loaded rounds check out fine, but those 2% can be a real problem if you don't check your ammo.
Like I said, the other calibers work fine, but the 9mm can be a bit "interesting". It is worth a bit of extra effort to make sure you don't have one bad round in a box of 50 that can give you a headache when you try to fire it.