Re: [GZG] Slightly OT - Hypothetical weapon question

On Wed, Oct 29, 2008 at 6:39 AM, Ryan Gill <rmgill@mindspring.com>
wrote:
> From what I understand is that different rounds
> will loose their integrity under different
> conditions or behave radically differently.
> Bullet integrity is strongly linked to not only
> the target struck, the speed at the time of
> impact of the bullet but also towards how the
> manufacturer designed and constructed the bullet.

Agreed.

> Some will fragment quickly, others will not.

In gelatin.  I am unaware of any firearms round designed for firing
through water from air, though I understand some special forces have
firearms (and rounds) designed for underwater use, I'm not aware of
any that are designed for shooting through water after being fired
above it.  This is more a statement of my ignorance of such things
than of their non-existence, but I try to be well-read.

> Take a look here and pay particular attention to the exhibits at the
bottom.
> http://www.firearmstactical.com/wound.htm

"Our goal is to instill a healthy attitude of skepticism in you so
you're not as willing to believe everything you read. Hopefully,
you'll learn enough here such that you'll be able to evaluate the
qualifications of so-called ballistics experts."

The above is the best part of the entire page, but firearms tactical
is an excellent resource.

"The entire missile path is captured in one or more 25 x 25 x 50 cm
blocks of 10% ordnance gelatin at 4�C. The penetration depth,
projectile deformation and fragmentation pattern, yaw, and temporary
cavity of the missile in living anesthetized swine tissue are
reproduced by this gelatin"

gelatin != water  (and, gelatin != reality, but it's the best we have
short of shooting living beings in tightly controlled scientific
experiments, something frowned upon nowadays)

You can't generalize the gelatin results to behavior in water.	There
may be some correlation, but that's just speculation.

> In the context of .50 bmg, I'd expect some API
> and AP in the mix for marine use. Those may yaw,
> but aren't going to break up nearly as quickly.
> Also, by the time they do start to break up,
> you're still going to have problems with the
> fragments carrying some velocity. More over, if
> it does yaw in the water, that just means it's
> going to key hole the hull side and not just make
> a nice neat .5" hole.

I don't think we have enough data to come to that sort of conclusion.
Unless you have access to an API and/or AP water test you aren't
sharing.  My very barely educated _guess_ is that shape and velocity
have more to do with water penetration than material composition,
based on the very small data set we have.

That all said, if I had a rifle or MG and I needed to punch holes
below the water line from above the water line, I'd sure give it my
best try and I would surely use AP rounds over something else as my
first choice, but I wouldn't be surprised if it didn't work.

-- 
Ryan Fisk
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