I research the Irish Family History Foundation's database. It contains 12,000,000 surviving rcds for abt 65% of Irish counties. Rcds are increasingly sparse B4 1840, rare B4 1800.
Note 1 - Without a KNOWN county, the chance of an ancestor's rcds NOT being in this database is AT LEAST 35%.
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).
For John Malloy B 1851 +/- 4 yrs somewhere in Ireland with the father's forename unknown, I found 109 rcds - too many to summarize here.
For Bar(tholomew) Malloy B ditto, I found 1 rcd in 1853, Co. Mayo.
For Pat(rick) Malloy B ditto, I found 60 rcds - again too many.
For Mary Malloy B ditto, I found 113 rcds - ditto.
My research was based on a DOB guess that John was 18 when he enlisted in the Army. All of the other searches used the same search range. You need to research U.S. censuses and naturalization papers to get better estimates of the DOB for these ancestors. Sometimes the latter also include placenames.
The military has kept all service rcds. Contact the National Personnel Records Center, Military Personnel Records, 9700 Page Avenue, St. Louis, MO 63132-5100. Go to its website, download an info request form, complete it, Mail the form and requisite funds to the address indicated.
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.