I've been bottling for 5 years and have seen a bunch of threads on wing vs. bench capper and people asking why their wing capper won't cap some bottles
I bottled a bunch of beer in Corona bottles when I first started out and then found that my Red plastic capper wouldn't cap them. They crimped and then were so loose I could flip them off with my thumb. I saved the day by unscrewing my capper bell and hammering it over the caps to fully crimp them.
The reason for the problem is that different bottles have different neck ring heights. I've measured up to a 3/8" difference in heights. The wing capper grabs the lower neck ring and uses it to pull the capper bell over the cap, crimping it.
Less neck ring height means that the crimper bell doesn't go as far down over the cap and thus, a less crimped cap. I went to a bench capper years ago because I have many different types of bottles
Here are a few pics showing what I mean
My standard red capper
You can see the difference in the neck rings on L->R, Modelo, Pils Urquell, Newcastle. The PU bottle won't cap at all with the wing b/c the bottle neck is as fat as the lower neck ring. The Newcastle style neck ring is the best style for wing cappers
Modelo and Newcastle have 1/4" difference in neck ring height
A Modelo bottle capped. The right side is flared up--not fully crimped. This cap was actually fairly tight. It may (or may not) have sealed