I have just read a few postings discussing the 627 Pro, so I hope this helps with some questions.
Here are my questions and the reply from Smith & Wesson:
I plan to purchase a model 627; either the Pro Series or a Performance Center model. (SKU: 178014 or 170210)
Questions:
- what is the cylinder gap for these?
- is the rifling and crown of the same quality on both?
- is there any reason 170210 will be more reliable over the life of the unit more than 178014?
- are there any MIM parts on the Performance Center revolvers and 170210 in particular? (I have no issues with MIM parts and know S&W is a quality product.) Curious due to the Chrome on the trigger, trigger stop, and hammer.
Reply from S&W:
The BC gap is .004 to .010, same quality and reliability, the parts are chromed MIM.
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My CNC products have a .002 or .003 cylinder gap, so I expect a 627 to have the same. My 27-2 and 29-2 both have a .003.
Muzzle crown is very important to accuracy. Don’t accept mediocrity. Remember, your revolver is a life saving device!
My research tells me MIM parts are injected (look up Rheology), however they are heat treated (metal conditioning treatments) just like the cast steel, et al., and has seen said to be made to look like case hardened steel, although my MIM triggers and hammers do not – they are a dull grey.
Note: Before I retired one of my many duties was Process Model Expert for software manufacture – (Quality Control, Quality Assurance, Process Management, Efficiency expert, SOP writer, etc.). Manufacturers use MIM because it works when properly done. Smith & Wesson says they do their own metallurgy. Their lifetime guarantee would not be viable if MIM parts did not meet quality standards. I have full faith in S&W and their ISO certification (quality control), because I know firsthand what it takes to get and keep ISO certification.
p.s. Back in the day, my first LEO issue side arm was a Model 19. I consistently hit 5 or 6 of 6 12 ga. casings from the 50 yard line (prone) using full power .357s. S&W revolvers are accurate; I like them, especially .357 Remington Magnum. It has been said a pistol is a machine, however a S&W revolver is a work of art. I like my art in the N frame.

Woodstock7