Took my little 22 R/F BSA Martini out for a gallop on Sunday and had five cases that would not chamber.
On close inspection the cases that would chamber came out at .223 for the cases and .225 for the lead.
For the ones that wouldn't chamber all the cases were ok and also the lead except a small amount just in front of the case which came out at .229 which makes me wonder if for some reason the cases were a touch longer and bulged the lead out a bit sufficient for them not to chamber.
Tried pushing them in with my finger with a lot of pressure until a quarter of an inch was left and then had to get a screw driver to ease tham out.
Definitely not the sort of thing you would want when shooting in a match or hunting if you haven't got anything to get under the rim to eject them.
Can't do it with a finger nail.

If a carbon ring it can take some work to get it out with JB and I would also recommend the same. Just wanted to let you know a couple of strokes might do it depending on how bad it might be and it could take quite abit more work. If you have a means to view the area it should be able to be clearly seen by just your eye. It will appear as a minute looking donut that doesn't belong there.

wipe it clean and relive with any of your fav. lube  art

I picked up half a case of Lapua Midas that will not chamber in a match chamber because the lube is like a rock. I have set up my collet style bullet puller and made a nylon holder that is cut to just expose the bullet. I compress it to the same point with the collet so it just pushes in to my rifle by hand. Seems to shot fine indoor, plan to try it at 100 and 200 soon since the weather (fingers crossed) is getting better.

Probably lube dry or lead oxidation. Wipe the bullets nose with a rag & sparse coat of Balistol. Might be surprised how well it shoots. I have some very old RWS R 50 that shoots good scores offhand. All with wiped noses. 

Boats

It has absolutely nothing to do with winning a match, a national championship setting a national record or any of my other own personal accomplishments by any means. It only has to do with cleaning ones own rifle for his own long term competitive use while also using JB. 
A fouled barrel has a multitude of abrasives inside of the bore and most just coming from the primers alone. 
When cleaning one does not want the cleaning patch to exist the bore and if so the abrasives will create a belled mouth and accuracy will then eventually fall off. When I clean my rifle I use 5 strokes in the first 1/3 of the barrel, 3 in the second 3rd and one in the last. This I was taught to do by a barrel maker and just not something that I made up. If doing so you will eventually create a choke at the muzzle or to maintain one that is already there. You are indeed correct in that something is indeed being removed but if one uses it to his own advantage it is a real good thing and not one that can become destructive to the rifles ultimate accuracy instead of. 
I am not trying to tell anyone what they should do but only what one of the best barrel makers during his own time had taught me how to clean.  We have been called to be the care takers of some very historical rifles and the proper cleaning methods for doing so are also a big part of just doing that. 

Hi Boats, 
I bought a whole brick of these a few years ago from a deceased estate which my shooting club sold off for his widow and now have three packets left.
I had another look at the offending rounds with a magnifying glass and could see no dried lube or anything else wrong with them.
Thought to try what you advised but but instead of a rag used fine wire wool. Brought the lead up nice and shiny and took all the lube of as well. Made a point of concentrating on where the bullet entered the case.
Tried chambering and it still wouldn't chamber.
The lead is nice and true to the case which is no different in size from the ones that will chamber and it is still my belief that something went wrong at the factory and either the case is a fraction too long making the rear of the lead bullet to bulge out or the bullet was pressed into the case too far also causing the lead to expand at this point where it enters the case.
If there was anything wrong with the chamber like a carbon ring it would surely affect the rounds that chamber ok.