- the site is incomplete for several western states
- patents represent federal land records only--the local courthouse has subsequent transactions which likely contain more information
- cash file entries contain minimal information unless there is something unusual about the transaction--the claimant died during the process, was actually filing a pre-emption claim etc.
And if you don't know your township from your section, read their FAQ first. The website is at http://www.glorecords.blm.gov