The Irish rifles are pretty distinctive by the square type front bases and the fact that the serial number on the right side of the receiver bridge at the rear is machine engraved and with W prefix (Britishicon are stamped and most without W prefix). If you still have pictures of your rifle, I might be able to tell you if the rifle without scope was made post WWI, or is an original WWI sniper.

Since all of the Irish rifles were sold to the US market plus we know of the Irish not only receiving newly made rifles but also leftover rifles from WWI it is obvious some WWI rifles were among those brought to the US market in aswell.