I reamed by hand.  Been so long ago I don't remember where I bought the reamer.  I have loaned it out to others on this site and always gotten it back.  If you would like to borrow, let me know guypalmer@bellsouth.net and I will see if I can find it.

I bought a 10MM reamer about 10+ (MAYBE 15) years ago & reamed the cylinder deeper to chamber 10MM Magnum in a S&W 610.  I use Starline brass to load 10MM Magnum ammo.  The revolver will shoot 40 S&W, 10MM Auto & 10MM Magnum with moon clips.  From my Ransom Rest it is extremely accurate with all 3 cartridges.  Don't remember loosing velocity according to my chronograph.  IMHO an excellent modification, at least to me.

I have a S&W 610 with a 6.5" barrel.  Bought a reamer and reamed the cylinder for 10MM Magnum ammo.  Bought lots of 10MM Magnum cases & Starline 10MM auto cases. Bought lots of "moon clips".  I shoot 40 S&W, 10MM auto and 10MM Magnum interchangeably with the moon clips.  Also have a Witness for the 10MM auto.  Have "too many" guns, so don't shoot it often.  Easy to manage, very accurate, sort of like to a 22 short, long or long rifle.  Love the gun.  Use a LBT LFN mould for 200 gr. bullets and Lee mould for 165 gr. cast bullets, cast from wheel weights with added tin, sized 0.401  Also have "too many" S&W 44 magnums, so not short of energy here.

Still have the reamer if anyone needs it.