The reamer simply does not cut to the end of the cylinder. This is a good thing in my opinion, as the bullet will leave the cylinder in the same diameter as the original tight s&w chambering, which is 0.224" by my pin gage measurement. Thus it will be just as equivalently centered in the forcing cone as the original "tight" s&w chambering provided - which is the whole point of having "tight chambers" in the first place... IE decreased bullet deflection from bore centerline and increased accuracy. Also note that the bullet will still be plenty big enough to get full advantage of swaging into the lands and grooves (0.217" and 0.222", respectively) so it will be biting as well as possible for good accuracy there, too. I ran a metal probe over the "transition area" you can see in the chamber, and it is NOT a sharp shoulder at all. It is imperceptible via the probe. The reamer seems to use a gradual slope for this area, it just appears to be a sharp transition in the photos because of the light.
There have been a few anecdotal stories of how excessively tight .22lr chambers may actually hurt accuracy, due to excessive leading/lube buildup. Here is another post on the subject. It deals with bolt guns, but I think you can extrapolate the principles to .22lr revolvers easily enough. Personally I think by chambering the gun in SAAMI standard, you get the best of both worlds, accuracy AND function. This is borne out by anecdotal evidence from those who have reamed their K22/Mx17...
Quote:
"A competitive bolt gun in 22LR uses a very tight chamber. I learned about all this working for Neal Johnson and Anschutz as a gunsmith on Olympic Target Rifles for resident athletes at the Olympic Training Center in Colorado Springs.
The throats on the chambers are short and they are tight. Match grade barrels typically run the minor bore dimension a couple thousanths tighter than what the SAAMI tolerance is.
This "chokes" the bullet and helps insure that it is running concentric to the bore's centerline.
Well, that's great on a bolt gun where you have a powerful camming action when going into battery.
Blow back operated semi autos won't put up with this, so it's modified to what is commonly called the "Benz" chamber. It's a compromise between the two.
The throat region is kept "almost" as tight while the back half of the chamber, the part that supports the case, is loosened up a bit to facilitate operation. (Feeding, chambering, and extraction)
The bullet gets the support it wants and the chamber will let the gun "run" right."
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I would go with a reamer before I polished. Why? Several reasons. One, well, because the chambers are already well polished from the factory. So what you're doing with the polisher to gain function is actually removing material. What that means is that you're doing the same job as a reamer but in an uncontrolled fashion. You might off-center the chamber, or eggshell it, etc. Yes it is tough to remove a lot of material by polishing but that is what you're doing in principle. I would save time, effort, and do it right with a reamer. If you wanted to have less clearance in the chamber you could call up Dave Manson of Manson's reamers and have him custom make you a slightly tighter spec reamer to use. Two, because highly polished chambers aren't actually necessary or desirable to begin with - unless you have a chamber that is so tight the brass will force itself into every microscopic nook and cranny upon firing, necessitating a highly polished chamber for shell extraction. In bolt rifle terms (or in S&W .22jet terms) the cartridge brass upon firing will grip the chamber less if it is polished, and will exert more force on the bolt (or recoil shield). This will result in much larger bolt stress (in a rifle) and/or inconsistency (in a revolver). So polishing is good for the bullet, but not so good for the chamber, unless absolutely needed because of a ridiculously tight chamber.