I guess it's sort of a fix, but as gcrank said, if it increases headspace, and I don't see how it wouldn't since the pivot is fixed, and it's not accurate, what's the point. 
Have you checked it for accuracy yet, or just ignition? If I understand your description, basically you're leaving the barrel partially locked up with less latch engagement which won't work as far as actually firing it with live ammo. 
Tim
Tim, I am confused as to your description
how can having the barrel sit 0.024" high, increase headspace?
the only thing I can think of is it will alter the breechface angle, but in this case, that may be bringing it to square, as the Firing Pin would be hitting more centered.
as you state, the pivot is fixed, so headspace is wholely dependant on the relationship of the pivot pin, and the recess, unless the lockup is grossly out of spec.
my understanding of lockup for breakaction guns is:
1) the barrel/lug has to sit flat and tight in the receiver and the bore needs to be perpendicular to the breechface, for proper bore orientation. On my .500 double rifle, the lug shelf is the watertable/shelf and is one solid piece of stuff, and the lever PULLED the chamber end of the barrels down TIGHT onto the shelf
2) the pivot pin and recess have to have the proper relation with the latch shelf, and latch to ensure a tight lockup when properly seated. but that comes AFTER the barrel is seated. the pivot/latch/shelf are just what hold it there.
if there is not a solid barrel/receiver seating happening, then closing the action with differing force would allow the barrel to sit at different locations based on where the shelf latch came to rest.
so in the above case, what now needs to be checked is EVEN breechface relation to the chamber/bore
ie/ same distance at top/bottom and sides. making the cartridge head square with the breechface.
I'm not sure the right way to check this, but one would need to spin a case on a known flat surface, and indicate off the shoulder to measure runout. perhaps setting on a known flat surface and using TWO small machine squares, and simply measure by eyeball with a measurestick laid across the mouth
once it is determined that the breech is square to the chamber, the work on the pivot pin/recess and latch shelf can take place. ( I am going to take a SWAG that if the Firing Pin strikes Center, then it is as perpendicular as it needs to be )
as the OP stated, all are firing good now, no FTF's I assume pin strike is more centered.
I'd be surprised if accuracy was worse, and would expect better, as long as there is no opening on fireing. and it is locking up tight.
next step after determining the shim thickness under the Lug, the OP needs to reduce the breech face/barrel interface to the minimum. This will probably require shimming the pivot recess.
Then smoke the shelf and work on proper latch engagement, thereby eliiminating any "Partially Locked Up barrel"
those things will give the OP a straight bore/receiver alignment, minimum headspace (perhaps too small if he is taking up 0.006) and strong latch engagement.
as the OP surmised at the start, perhaps the barrel was OVER locking, and now he has just corrected that.
and that should make for an accurate shooter.
Can you walk me through this to help me, and perhaps others to understand?
didn't Fred M do some receiver bedding accomplish this same thing?
watkibe: can you post a couple more pics of the pin strikes with shims in place?
thanks
'nuk
