There are several additional posts pertaining to that same question in the archives. If you do a search, you should come up with some answers. I asked that question myself several months ago. Here's what I came up with:
1) the standard .22 LR barrel is just fine, but there seems to be a number of standard barrels that just will not shoot.
2) I have heard no one complain about the .22 LR with the Match chamber, they seem to all shoot very well with the proper ammunition (each barrel ceratinly likes different loads).
3) It may take several different loads/brands of .22 ammo to come up with ideal performance.
I have personally never shot a standard chamber .22 LR in a Contender. I recently purchased a NIB 14" .22LR with the Match chamber. Got a good deal on one, and decided not to take any chances with the standard chamber (based upon what I've been told). Again, there is probably nothing wrong with a standard .22 barrel. I do know this much-my brand new barrel (with El Cheapo Red Dot) will shoot an entire box of shells in a 2" by 2" square from 50yards and a solid rest. That's more than MOS for me (minute of squirrel).