Bullet bc. Length
69smk .323 .900
69tmk .355 .982
77smk .371 .994
77tmk .395 .994
All from applied ballistics
So the 69tmk has a bc close to the old 77smk, but is only slightly shorter.
77tmk has a better bc and is the same length.
Do the tmk shoot as good as the smk?
Seems like for an AR15...