Well, I don't know who supplied the lock. It was on a rifle bought from a well known maker. The lock is marked L&R, and it may be only about 15 years old, maybe a bit less or a bit more. I don't keep track of time, or what was bought when.
IMHO, the issue isn't so much about poor construction as it is about poor design and what appears to be a too hard frizzen.
I understand that L&R tried to make a faster, more efficient lock by reducing the rotation of the cock, in addition to attempting to direct sparks into the pan by designing the cock to stop the flint close to the pan. The problem with this design is that flints have to be just the correct length, or the pan won't close at half cock. A slightly too long flint will also bash into the pan.
I buy flints at events, where I can see what I'm getting. Unfortunately the flints available at those events are pretty much square, so finding flints wide enough, as well as short enough is a real pain.
The back of the leather holding the flint is notched, but I gave up on notching the flints, themselves, since this gun goes through flints so quickly. IMHO, Notching flints is waaaayy too much trouble, so flints bought for this gun run small, but even 5/8" wide flints are sometimes too long.
I mention, again, a Manton lock bought a over a year ago. The sear screw hole was about .010 larger in dia than the sear screw. The slop was so bad that the sear was canted to one side, just from tension of the sear spring, to the point that the nose of the sear did not make full contact with the full cock notch. There were other issues with this lock, but that was the most obvious, and potentially the most dangerous. An oversize screw would have corrected that problem, but little on this lock was right.
I do know that a number of people do send current production L&R locks to LC to fix 'em right. I thought of sending the Manton to LC, but couldn't justify the expense for a lock that should work, out of the box.
You must be exceptionally blessed to not have received a bad lock from L&R. The few I have bought, directly from L&R, have all had something wrong with them. Those issues, with all but the last were fairly easily corrected with replacement parts and/or heat treating.
I'm not the only person less than satisfied, through personal experiences, with L&R locks. All of us can't be wrong.
God bless