The 70's... lets see, based on bullet length and the rule of thumb that says keep the diameter of your bullet in the case neck, that would have put this bullets "ideal" at about 2.690 or even 2.695". I can tell you I've shot these out as far as 2.710 without being even close to touching the rifling, and my COL on this load is all the way back at 2.620 - so a lot of jump. This gun just seems to prefer more jump than usual, for whatever reason. Same with the 80 SBT's I've shot, same with the 85SGK's, etc. But I would have to look back through my notebook another weekend to see exactly what COL these 70BT's touched at - can't recall off the top of my head. I haven't chrono'd this load yet either, but I have to believe this will be 3,400fps or better.