The barrel is holding into/onto the receiver by the locking bolt connected to the top lever, the position of the top lever is an indicator of how far the locking bolt is wearing into the locking lug (s).
When the top lever pass the center position to the left, the locking bolt is close to it's end of travel (life).
Until the barrel starts to wiggle (even very little) after action closed, it's still safe to shoot the gun.
Some designs will let you change the locking bolt to a bigger (thicker) size to compensate it's wear, some you'll have to rebuild the lug (s) up to bring back it's tightness.
Opening and closing the gun, firing, etc. Giacomo recommends: holding the top lever with your finger, close gun, let the top lever go. Do this instead of slamming the gun shut. This will help the life of your top lever.
I went the other route, we weld up the locking lugs to meet the bolt.
Because the locking bolt is harder than the barrel lugs, it wears down the lugs (in Browning case, one lug), that's why you'll need a thicker bolt to meet the worn lugs.
By weld up/rebuilt the lugs, we bring the lugs back to original size to meet the original bolt.
Another reason for this is because a new Perazzi bolt is more expensive than rebuilding the two lugs by my guys, and the bolt is not always available in the right size.
This can be done with any qualified gunsmith on any shotguns without finding and stocking different brands and sizes of locking bolts.
Second question's answer: 7000 rounds will not wear down any halfway decent shotgun, I don't know about 90T, but it'll take over 50,000 rounds to move a Perazzi top lever, and usually the wear was caused by keeping the bolt dry.
I have a Citori Plus that is left of center and may have always been that way, I don't remember. But, If I wanted to have it "repaired" who does it and how much are we generally talking abot cost wise?
Rebulding a locking bolt is about $125...at least, that is what I charge. This also includes a complete clean & oil. If you what new springs installed at the same time, the only additional cost is the price of the springs.
Your top lever shouldn't have been in the center. Because I did most of the patterning and final inspections, I'm sure I would have caught that. You're saying the top lever is sticky....there was a locking bolt angle change during production from 10 degrees to 8 degrees. I could be possible the 8 degree angle could be slightly less. This definitely would cause a sticky top lever. Is your serial number above ST02700? That was about the time the change was made.
H Daddy, I respect that. As I said, "you're running the risk of..." not definitely bond to happen.
I say this because I noticed on some of my guns, if I hold the lever while closing, the top lever stopped more to the right than I let it close by it self, this shows it's not fully engaged.
I close my guns like most of us, including Miss K. Rhode with her over a million rounds MX-12, not holding the lever. Never had a problem with the top lever moving toward center within 50,000 rounds, her gun was first rebuild by Perazzi USA after 200,000 rounds. I don't have too much experience with every other makers, but I was quite lucky with the guns I have.
As you mentioned, our friend PBB Mike always said: All Good.