More .22 LR shooters need to try a mix of ammo in their rifles to see what really works. At 50 and 100 yards, you can really see the difference in the high grade match ammunition, and see how good your rifle really is.
Chambers and rifling are different. Sometimes the cheaper ammunition shoots very well. An example of this is the S&W M&P 15-22, a .22 LR clone of an M-4 military carbine. They have tight chambers. Smith & Wesson recommends the bulk Federal LR standard velocity, because it is sized just like their Gold Medal Match. I shot Eley Tenex, Federal Gold Medal, some Rem and Win and CCI, and sure enough, the inexpensive ( pre-Obama ) Federal Standard .22 LR functioned and grouped closest to to the match grades.