I have very little experience but I'll throw in my two cents based mostly on reading what others have said on this topic.  If you look at the specs for the dozens of 22 L.R. reamers that are available, you will see that there are are about four variables-base diameter, neck diameter, lead angle, and length.  Since most falling block actions have very little camming action, I believe that length is the one factor that is most important.  With that in mind, when I recently chambered a low wall I used a PTG Match reamer which is rather long as match reamers go...I believe it is .630 as compared to others that may run as short as .590.  It is still tighter in all dimensions than a Bentz reamer which is probably also a good option for a falling block.  I believe that with the Calfee reamers, there is no rim cutting area so you can run it in as far as you want then cut the rim afterwards (or before).

     The Bentz reamer is designed for semi-autos.  It has tighter tolerances than a standard 22lr chamber, but is still loose enough to cycle reliably in a semi-auto.  In my experience (with building semi-autos) a standard reamer will print a 2.5" group at 50 yards with standard ammo, where as a Bentz reamer will print 3/4" groups with the same ammo.
          Match reamers were designed for more accuracy, but the chamber is usually shorter.  Match reamers are usually used in bolt actions, where the camming forces of the bolt can seat the bullet into the rifling.  A match chamber might be too short for rifles other than bolt actions.
         A standard reamer will make a chamber which will accept anything, but with less than stellar accuracy.

Hard to argue with Calfees success and the records set by the rifles he built. A rifle that shoots fairly well might be good for hunting but it won't consistently win you any honors in competition. Rimfire success is very dependent on the ammo used and I would assume Calfee designed his chambers to take advantage of what the best has to offer. Calfees success is legendary in the world of rimfire benchrest shooting and looking beyond his chambers one needs to understand his means and methods for checking and accepting a barrel blank as well as its ultimate length.

If you want to win do as the winners do!

JLouis

Sounds like Calfee is using this reamer:

22 FREELAND MATCH   .2242 base, .224 neck .600 length, leade 2°, Rim .288

It's what I design my reamer after but, changed the leade to 1 degree and w/o a rim.

Frank

I'm of the opinion that proper chamber design is important,  but it has to fit the ammo.  Other wise you are trying to make the foot fit the boot, rather than buying the boot to fit the foot.
When I had my #1 ruger converted to 22f for the 200 yd "single entry"benchrest 22f ASSRA Match.  Steve Durren asked my what ammo I was using so I gave him a sampling of a couple lots I had on hand.  I do not know which reamer he may have used.  I know he has several on hand. but he matched it for a tight fit. the round has to be pushed in the last couple 10th and when I have carefully pressed one back out with a rod the bullet is almost fully engraved.   I have long since used up that batch and MFG but I have used it pretty well with several other types of quality match ammo with (for me) pretty good success.  I have to use a wood "pusher" to seat the roads before closing the action. 
 at this point I pretty much figure the rifle and ammo are about optimum----the shooter----wellllll

If memory serves me right Calfee's reamer was of a proprietary design and thus not offered for public use / the reamer makers can not make and sell it to anyone else under those circumstances.

JLouis