Can't speak to the Sierra 6.5 mil HPBT's but use the 6 mil HPBT (85 grain) Sierra's in my 243 - kill deer dead (within 100 yards - never had to shoot further) - expand well.
Can't imagine that the larger/heavier version would be "ineffective" - it's a sound design that has probably taken thousands of deer over the years.
You can spend a lot more on bullets and the deer aren't any "deader". At your stated range of 150 yards (or less), you don't need fancy/expensive - these should be fine.