The men in the Carey Haplogroup R1b Lineage 1 are part of the Irish Type III subclade. Dennis Wright maintains an excellent web site devoted to Irish Type III here: http://irishtype3dna.org/index.php
He and Dennis O'Brien also maintain another site devoted to Irish Type III and its confirming SNP marker, R-L226, here:http://www.familytreedna.com/public/R-L226_Project/default.aspx
Both sites have spreadsheets which show the DNA information on all members who have consented to share that information. The R-L226 Project site groups the DNA results of closely-related men together. We Careys are in Group B, near the top of the spreadsheet. Only two Careys are shown at this time, but three more will soon be added. As you can see, we are most closely related to three O'Briens, one Bryant, and one Hart. We are much more closely related to them than we are to any other Careys in the Carey DNA Project. Why is that? Mysteries like that are part of what makes genealogy so fascinating.
An interesting fact about the members of the Irish Type III subclade is that their DYS 464 sequence is almost always 13-13-15-17. In fact, prior to the R-L226 finding, the 13-13-15-17 sequence was one of the markers used to determine membership in Irish Type III.
The Careys in Haplogroup R1b Lineage 1 stand out as the primary exception. Their DYS 464 sequence is consistently 13-15-15-17. That anomaly offers us a great opportunity. There are very few men who are both Irish Type III and have the 13-15-15-17 sequence. As time goes by, and more men are tested, we should be able to determine approximately when and where this significant mutation came about within Irish Type III. That will give us some additional clues about Thomas the immigrant's ancestry, and enable us to better focus future research.
The recently-announced "Big-Y" project may result in the identification of additional SNP markers which would allow researchers to break the R-L226 group down into several sub-groups. Keep an eye on the Irish Type III web site for breaking news in that area. Dennis expects to see some results in February.
I encourage you to reply to this message if you have any questions or comments.