Eley's Tenex is one of the best  for weight consistency of their .22 LR ammunition. The distribution for 1515 rounds was:

3.29 gm.  4X        0.3%
3.30 gm.  355X  23.4%
3.31 gm.  520X  34.3%
3.32 gm.  626X  41.3%
3.33 gm.    10X     0.7%

The lowest and highest weights were borderline and could have been 3.30 grams and 3.32 grams. This may not have been variation of the ammunition but may have been the accuracy of my weigh scale. But there definitely is .3 grams variations in this lot of ammunition.

What degree of precision in the quality do you expect from the most expensive .22 LR ammunition? Is any variation in the ammunition's weigth important?

Dave is this the new tenex.....as in late 2008-- early 2009
I just got a new case from machine 3 and this new stuff sure looks a lot neater --- as in nicer crimp -- cleaner bullet ---wax stops one band ahead of the case.
haven't had a chance to shoot yet on a good condition  or haven't weighed any yet but it sure looks better then the 2006-2007 stuff.....
we'll see...
SST

It is generally thought that weight varience and rim varience are, for all intents purposes, not going to give you measuable accuracy issues in the higher 3-4 grades of Eley and the higher couple grades of Lapua. In the single shot world you are probably dealing with bigger variences of ignition and firing pin design. If possible you might want to lot test before purchase. It's all pretty good these days but some barrels seem to do better with one lot over another IMHO. The good news is that the current Eley has great average lot performance, it's pretty easy to get good stuff these days.

Rim Thickness:

.0370"   3.3%
.0375"  26.7%
.0380"  51.7%
.0385"  18.3%

I am shooting 22 Short Target cartridges in a Winchester.  Not nearly so many types to try.  About all that is affordable & available are Fiocchi Super Match and CCI Target Shorts.  The CCI stuff is relatively uniform, in both weights & results.  The Fiocchi, if sorted by weight, will shoot tighter groups than the CCI stuff.  If you do not weigh & sort the Fiocchi, do not bother to shoot it.  Because it is a Winchester with the spring-loaded anvil & ejector, measuring rim thickness is an exercise in futility.