I research the Irish Family History Foundation's database. It contains 12,800,000 surviving rcds for abt 70% of Irish counties. Rcds are increasingly sparse B4 1840, rare B4 1800. Cos. Donegal and Derry were recently added to the database.
Note 1 - Without a KNOWN county, the chance of an ancestor's rcds NOT being in this database is AT LEAST 30%.
Note 2 - Only 1/2 of Co. Cork's rcds are in this database.
Note 3 - The RC church kept control over most parish rcds from Tipperary (north). These are ONLY available thru the Tipperary Family History Research center at a substantial fee (regardless of outcome).
Note 4 - Microfilms of parish church rcds are kept by the National Library of Ireland.
Co. Offaly rcds aren't in the database yet. Suggest you wait until they are. Currently, there are 810 Kinahan B rcds dating from 1751, and 343 M rcds dating from 1737. Offaly was one of the last areas to be pacified. The O'Connors-Faly raided as far as Dublin in abt 1610. Hence, it is unlikely that early B/M/D rcds exist there.
Google the Foundation's name to lead you to this database. Register, opt to be notified as rcds are added and browse. Pls post your search results to my genforum msg.