I've just added a Bolt found by chance while there in Sept:
Mullach Sgar: http://www.trigpointinguk.com/trigs/...ils.php?t=7548
Checking the OS trig archive, there are (or were) ten assorted trig points on this small remote island.
2 others in NF0998: Clash na Bearnaich and Na h-Eagan (the latter destr 1965).
Someone also described what sounded like a Bolt on The Cambir at NW end of Hirta, while we were there in Sept, although I didn't happen to notice it when I was there and the OS archive lists nothing in NA0700 or 0701.
Other Bolts listed in the OS archive are at NF0999 (West end of Base); NF1099 (East end of Base and Oiseval);
Claigeann Mor http://www.trigpointinguk.com/trigs/...ils.php?t=7508
St Kilda S8820 http://www.trigpointinguk.com/trigs/...ils.php?t=6131
2 other trigs also also listed near the pillar in square NA0900: Conachair (rivet) and Mullach Mor (bolt)