I reloaded a bunch of 9mm a while ago. I just shot most of them off last weekend but the Beretta I was using wouldn't rechamber. Is there any other explanation other than a too light power load?
Was this a failure to feed, like the rounds were not stripping off the magazine, or was it the gun wouldn't go fully into battery?
How much crimp did you use? 9mm needs a taper crimp to perform best. If you take the barrel out of your gun does a round drop freely into it and then back out again when you turn it over?
Is the fired case extracting and ejecting? If not it may be short stroking which means you have (1) too much spring and/or (2) too light of a load or possibly (3) limp wristing the gun.
If it is only not feeding, where is the round stopping? Is the nose of the bullet on the feed ramp.?if so, a light polish with 1000 grit sandpaper wrapped around an empty case works well. Also, if the magazine is old/used, a fresh spring can work wonders here.
If the round is catching on the barrel hood, look at the magazine's feed lips. If they are too far apart, this can case a premature jump to the barrel.
Also, what OAL are you loading to? Check the OAL of the reloads to a similar factory load (e.g. Winchester White Box). If you are on the short end of the range, try running it out a little bit. That, generally, will help smooth out functioning issues.
I wouldn't toss the book out just yet. As has been asked, what exactly is it that the gun won't do? I makes a difference. When you say it won't "rechamber", what do you mean? It stovepipes? Fails to eject? Won't go into battery?
Give a little more info and I'm sure we can find the culprit.
It wouldn't fully eject the spent brass. Seemed like a pressure issue to me. Other mfg bullets worked fine. In my book it said that 4 gr was starting point and 5.2 max. It is a really old Lyman's book.
You may be right. If it wouldn't eject spent brass it is possibly loaded too lightly or you might be limp wristing. If other rounds don't cause the issue, I'd say you found your gremlin.