I don't think it's the extractor as the round is stuck under the the feed rail still before it can pop up--there's a step in the feed rail that allows the round to pop up under the extractor, but when the belt of the round gets to that step it binds/jams--- a double stroke will sometimes get it to feed and other times it won't feed with a double stroke---

I'm going to look at my CZ 375 and see what kind of side to side play there is of the rounds as they're in the mag box--if it's tight then I don't think there's anything to do concerning the Lott mag box unless the stronger spring fixes the prob-- a thought just came to me, since I massaged the follower the last two rounds feed great, so maybe the rounds have some side to side play now which allows the round to clear the feed rail step to be chambered---if this is the case then widening the mag box/feed rail for some side to side movement of the rounds may be the answer--I need to see if there's play in those last two rounds--this may be the answer--

if not then the next step may be to attack the step in that feed rail, which to me looks like if I move that step back an 1/8" or so the rounds would feed, what are the downsides to doing this--the rounds won't stay in the mag box is about the only thing I can see happen, but I think by just moving the step a little this wouldn't be an issue, but since the last two rounds feed pretty good now I really need to think this over, as why do they feed and not the other rounds--is it because I have side to side play in those rounds now???

finally would be to go after the ramp height--but this is the most tricky part of all, because you would be messing with the bearing surface of the locking lug once the round is chambered to be fired--- I don't know how much can be taken away from the ramp height before you have mangled your action--it may be gunsmith time at this point--chris