Sure. But they're not necessary, and it's not clear why thomas15 said so.
True they are not necessary. In the context of this discussion we were looking for ways to improve performance and speed, not slow it down. Sorry you missed that point.
Of course, now the individual purchases a brand new Performance Center revolver and takes it out shooting even in a friendly get together and then the oh so happy individual with an ear-to-ear smiles invites a fellow Performance Center revolver owner to try out his brand new gun. On inspection the fellow PC owner dude states "nice but what's with that trigger"? Perplexed you ask innocently "what do you mean "what's up with that trigger"". Fellow PC owner dude responds back "you have an approx. 14.739 pound trigger pull and you are asking me to explain?" "Did you not notice this or inspect the pull with a trigger scale?"
After what seems like a year of awkward silence, you sheepishly respond "this is a S&W Performance Center revolver, it is hand crafted and ready for the National Matches!"...(pause)... "Not only that, the single action trigger is smooth as "ice on glass!""
(more awkward silence)
"I hate to break it to you son" fellow PC owner calmly retorts. "You have a really nice gun that has lots-o-potential but it's not hand crafted at the factory and it's certainly not ready for anything even semi-serious never mind the Nationals". "Here, try this" as he hands you his 627 PC revolver. At the safe table you give the trigger a few pulls and cannot believe the difference. Fellow PC owner dude has an approx. 6.739 pound trigger in double action and there is no hammer spur to even contemplate a single action trigger.
"My PC 627 isn't like this gun!" in anguish you cry out.
Fellow PC owner dude informs new PC owner that to the serious or even semi-serious revolver shooter, these guns are really "kit guns" PC label and price tag not withstanding. "Son, if you want to unleash the potential of that new Performance Center gun it's going to involve opening up that wallet and having a revolver smith lighten up the trigger and smooth out the action". Lighten it up to where mine is, about 6.5 pounds then you will be required to shoot only handloads with Federal #100 primers seated below flush. You are of course free to try CCI or S&B primers on sale at Cabelas but if you want to hear "bang" and not "click" it's Federal primers".
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So the two fold moral of the story is S&W PC revolvers are not what you think they are and if you are going to put the money into a new PC revolver to make it a competition worthy firearm, then you are going to handload your ammo anyway, you really should consider 38 long or short colt brass and moon clips. Not doing so is like putting regular gasoline into the tank of your Mercedes Benz C-300 with 4-MATIC. The motor will run but it will run like crap.
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To put the question asked by the OP into dollars and cents, here is what he is up against (this is not an exact price list so don't nit pick it):
$1050.00 Cost of S&W PC 627
$400.00 Cost to have a revolver smith tune the action, lighten up the trigger, bob the hammer, chamfer the charge holes, ball detent in the crane open position, ….otherwise work his magic.
$50.00 Cost for a red dot mount.
$200-$500 cost for red dot sight (note: the included factory iron sights work but they suck)
$4.00-$8.00 X number of moon clips the shooter wants to have (note moon clips are to a certain degree brass headstamp specific.
$100.00 for moon clip tool(s)
Options that are nice to have but not necessary:
$80.00+ to replace the factory grips
$80.00 to replace the factory thumb latch
$50.00 for a good two piece (inner/outer) belt
$100.00-$250.00 for a good holster
$100.00-$250-00 for belt mounted moon clip holders
$40.00 for Lee 38 long/short Colt die set
$100.00 for 1000 pcs Starline 30 long/short Colt brass
Notice how the purchase price of a PC revolver becomes sort of lost in the cost of the overall adventure? So, lets say that to get a new in the box S&W 627 PC revolver ready is going to cost at least $1500.00, probably close to $2000.00 depending on what ancillary items the individual needs to acquire.
On another popular thread on this board there is a discussion about shooting single action quickly. It is true that an individual that shoots a single action revolver can perform a reload quickly. But quickly is a relative term when shooting on the clock with good solid revolver shooters shooting double action with moon clips. Practice anything long and hard enough the individual will become good at it. This applies to shooting and reloading single action revolvers in a double action moon clip world or shooting a 6 shot revolver in an 8 shot world.
Have a wonderful day!