I have found two old rimfire cases about 40 caliber or so. I have not measured them and they have been fired but were misfires, copper cases . where on the net can we find out more on old cartridges like theses? Thanks

www.cartridgecollectors.org is the website of the International Ammunition Association.

Rimfires run from 2.34mm on up (the largest in my personal collection is 56cal)
In the "40" range the common ones are are 38, 41, and 44 cal RF's (several varities of each)
The nice thing (if you can call it that) is that the majority are made with "heeled" bullets, so even with a damaged/eroded bullet measuring the casemouth will give you the origional bullet diameter (within a couple thousanths).

BTW, if yours is a "bottle neck" design, it's most likely a Swiss Vetterli round.

Rem,

A picture is worth a thousand words. The rim diameter, case length and bullet diameter are the most important dimensions, although sometimes others are needed. Post this on the forum you will find on the IAA site (Tailgunner's reference - you have to register) and we'll see if we can fix ya up. Please keep the photo to 900 pixels width or less and be sure it is clear / not dark. Rimfires are sometimes a challenge to identify because of the lack of markings - and especially with the early ones, very sloppy tolerances within and between manufacturers for nominally the same loading . . . not to mention, as with CF rounds, sometimes the different loadings are virtually identical with tolerances in multiple characteristics overlapping.