by eyeball and "coin gauge", centerpin extensions -
(NO, the centerpin does not extend any further when closed, than when open. If it somehow even could, that would be a different problem, not unlike crud under the extractor which can tie up the cylinder.)
my INA snubbie 32 extends the thickness of a nickle, ~ 1/16"
same as my old model "LNIB" S&W J-63
a S&W k-66 about half again that much, about a nickle plus a dime, ~ 3/32"
same for a S&W k-48, nickle & dime ~ 3/32"
my Hi Standard Double 9, longest centerpin extension of any I just gave a quickie look, almost a double nickle, though not quite, mebbe ~ 7/64"
1/8" is a lot (a double nickel), no kidding... and 1/4", I would doubt any DA revolver pins are that long, unless somebody can list one
(some hefty magnums, or SAs, mebbe so, dunno)
No reason a nickels worth (~1/16") should not be plenty enough
1/16" = 0.0625", 62 thousandths, that's like 10X the b/c gap
In the bolt hole is... in the bolt hole; it would surely take a mega-monster magnum load under recoil to allow centerpin spring compression of only 1/16", if such can or does happen. There is not much inertial mass in the little centerpin.
All my S&Ws (rimfire or centerfire), again as MrB said, stouter centerpin springs, clearly a bit harder to push in flush with thumb. But I am 'hard pressed' to believe that is your problem.
Not much to cause that pin to wear down either, short of taking a file to it.
They all have a 'scar' mark, on the arc path the pin drags thru on closing. more pronounced than the drag turn line on the cylinder exterior you know. (The one on the rear frame face is not 100% 'wear', really). Dunno how to 'gauge' the depth of that observation, though, it should not be deep, seems unlikely it would be.
If is is real well lubed, with nothing about extractor, pin, or bolt being the least little bit sticky...
heckifiknow
some pictures, maybe ?
PS
TIP - the centerpin extension into the bolt hole w/ cylinder closed simply cannot be any longer than the allowable forward travel of the thumb release
on mine, the thumb release can only move just very barely more than a nickel thickness forward, before contacting the rear of cylinder shield
hence, "a nickel's worth" of movement is all you get, period
(otherwise cylinder would not unlatch, because you simply could not push the bolt/centerpin out far enough for flush-to-frame face, to unlatch)
IF yours only has that much thumb release travel, then you centerpin is not too short
you never did say what caliber yours is, though