When a bullet travels through the transonic range the frictional pull trying to
slow it down is from four to five times greater than the pull that exists at
subsonic velocity. Simply put, this differential pull causes instability. A
stable, round-nosed, flat-based bullet (like the .22 LR) will he less accurate
in the transonic range. Inherently unstable, hollow-point, boat-tailed bullets
(with the preponderance of mass to the rear) will lose all stability in the
transonic range, tumbling end-over-end and losing any semblance of accuracy at
that speed.
Thirty years ago, those who drove Chrysler vehicles on slippery roads in the
northern states found that, in a situation where control was lost, the vehicle
would spin and settle into a rear end-first attitude, because the rear end was
heavier than the front end. Those who drove Ford products (which typically had
less rear-wheel traction on ice) soon learned that the heavier front end caused
the vehicle to be more stable in a spin. Its natural movement in a minimal
traction situation was front-end first. Sharply pointed bullets have the
heaviest end at the rear, and they take a much greater spin rate to keep them
pointed in the right direction. Bullets with blunt points and hollow bases (Like
hollow-based wadcutters) are inherently stable in flight. They fly straight,
even without spin.
In terms of effectiveness on live targets, it is very hard to beat a blunt-nosed
or flat-tipped bullet. Put another way, a subsonic bullet that is a true
cylinder will deliver more shock, hemorrhage and trauma than any other shape.
Sharply pointed and round-nosed projectiles will slip right through, while
causing minimal damage. It has been said that some .30 caliber projectiles are
designed to expand at 300 m/s or 1,000 fps, but this remains to be proven to my
satisfaction.
(not neccesarilly my opinion...just something I found from Finland where they do a lot of work with sub-sonic and suppressed loads)
Sharply pointed bullets will penetrate deeply at subsonic velocities - pushing
nerve tissue and blood vessels aside, rather than cutting them. Unless the
bullet hits the base of the brain or a major nerve center, the animal will run
away, usually to die a slow and agonizing death. Most pointed and round-nosed
.30 caliber rifle bullets are totally lacking in knockdown power at subsonic
velocities. We hear the same stories of subsonic .30 caliber bullet inadequacies
over and over again, and are frankly quite tired of them. Subsonic .30 caliber
bullets will not expand in large animals. The only effective .30 caliber
subsonic bullet will have a totally flat front end.
...another little excerpt, very interesting...the birth of the Whisper?
The next step up the ladder of higher subsonic energy is the move to a .30
caliber weapon. The .308 is a logical place to start, and (with a light charge
of fast powder) it can he effective in a weapon that is designed to he both
subsonic and supersonic. A 254 mm or 1 in 10 inch twist will stabilize up to a
200 grain, round-nosed, flat-based bullet. However, the extra room in the .308
case provides a substantial cushion, which can cause problems with efficiency
and consistency. The most ideal situation results when a cartridge case is just
big enough to hold its charge of powder and a bullet, with no room to spare. In
the 1960's a fellow named Joe Apache necked a .223 case up to .30 caliber. The
result was an interesting cartridge called the .30 Apache, which sat ignored for
quite a number of years.
