You didn't say what kind of ammo you are shooting / but something is very odd here if you keep having the issue and you have replaced the pins this many times. I have a lot of Browning O/U's with thousands of rounds thru them with no firing pin issues, so I'm comfortable telling you it isn't a model specific issue - and in my opinion its a general firing pin condition issue.
I have seen what you're describing happening on Brownings - and other guns - that shoot a lot of chedite primer loads - on reloads and on factory ammo / but the guys that I have seen with these problems changed the firing pins and their loads and the problem went away. I have also seen guns, including many Brownings, that shoot a lot of reloads, with Chedite primers, and the pins have showed no wear at all - including mine.
I suspect Browning went thru a couple of years with some bad firing pins - where they must have been heat treated improperly and I don't know if they were too soft or too hard / and like others suggested, I would try and give them a call and see what they recommend.
But how and why this is still happening to you after you've replace them so many times is really a mystery to me - unless Browning doesn't know how many bad pins are out there in the parts inventory.
All of my primary target guns are Brownings ( 6 XS Skeet models in 12, 20, 28 and .410 ) and 2 XT models for trap ..... all 8 were new guns purchased from 1995 - 2006 / and I purchased a used XT last year that was made in 2005. All 9 shotguns get checked twice a year, at least, and no pin issues on any of them - and from 2005 - 2007, I was using Chedite primers on my reloads in all 4 gagues ( before I heard about/and saw some of the problems caused to firing pins). My primary 12ga guns have at least 4 - 8 boxes a week thru them during that period for a solid 8 months a year so a minimum of 3,200 shells a year thru those guns or at least 10,000 over the 3 year period with Chedite primers....and probably more like 15,000 shells over the period.
I have long suspected the issue may be affected by some of the ammo coming in from overseas - Fiocchi, Rio, etc - with corrosive primers / or something in the primers that is affecting the firing pins. After you talk to Browning / I would suggest you talk to someone like Brownells and see if they have firing pins / or see if Browning will ship you a set of pins - keep the packaging, after you install them, note in a journal what loads you're shooting, etc - so if you have another issue down the road, you can contact them again and see what they say. I'm going to be very dissappointed in Browning if a new set of pins doesn't fix this problem once and for all / or some combination of replacing the pins and springs doesn't solve it for you - I can only imagine how aggravating it must be.
idk wether it is the shells i am shooting, the amount of shooting i do or just the pins were bad from the start.