What data do you have to support your comments that all bullets fired into fluid will land tail first?
I have not seen this to be true, in fact it depends largely on the way the bullet expands or does not expand.
The longer the bullet as it penetrates, the more likely it will tumble while it penetrates. The shorter the bullet length the less likely it will tumble, again this is my experience at least as far as on game penetration goes.
Some will tell you that a forward center of gravity on a bullet will be the most accurate, that may be to a certain yardage point but at extended range, again, from what I have seen, shifting the center of gravity to the rear really seems to help with long to extreme range.
All one has to do is look at all the bullet designs out there that are designed for long range shooting, all are either HP designs with large hollow cavities in the nose or they use some type of ultralightweight tip on the nose to accomplish the same thing.
These designs also add BC because they add length to the bullet. THey do this without adding much weight at all to the bullet either.
I guess the best minds out there have tested this and always come back to the similiar designs we have today.
I have seen some tests with tear dropped shaped bullets made by the military. Looked very similiar to what you would have if you took a conventional bullet, put a round on the boat tail end with a sharp nose and then turned the thing around and fired it round end first.
From the tests I read on these bullets, BC was extremely accurate but it did not compete as far as having as high of a BC as a conventional VLD design. To that point, most flat points and round nose bullets have much more consistant BCs from shot to shot then any VLD or ULD design, only problem is that the BC is extremly low.
There have also been the hollow base bullets that used to be used many years ago. They were relatively accurate out to moderate ranges but really lost if at any extended ranges.
again, I am by no means an expert on bullets, hardly but there have been alot of tests done to find the most efficent and accurate projectile design and what we have now is the top of the pile unless you get into self stabilizing projectiles which is not practical in conventional small bore designs, not yet anyway!!!