Yet more nattering about .300 Whisper.
(If you're not a terminal ballistics geek, this post will probably be as dull as watching paint dry. I won't feel bad if you skip it, but if you've read this far and are of a masochistic bent and wish to read further, I'll try and supply definitions as I go.)
On further reflection, the 220gr loading should make a pretty fair House Gun round. Here's my reasoning:
1) Sure, the bullet is a weak sister compared to rifle cartridges, but think about it: 220 grains, 1040 feet per second, 500+ foot-pounds of energy. Nobody ever accuses the 10mm Auto or .45 Super of anemia, and these numbers would be right at home with either loading.
2) Those 220 grains are in a .308" bullet. That's a lot of sectional density. (Sectional density is mass relative to cross-section.) Sectional density is what makes for penetration in bad guys.
3) The 220gr projectile is of a long-ogive, VLD (Very Low Drag) configuration. This means that it has a long, pointy nose and a center of mass that is well aft. These are the things that cause a bullet to have an early yaw cycle ("tumble", in layman's terminology) on impact. (Basically, this means that the big, long bullet will, almost immediately on impact, yaw through 180°, shedding energy as it does so, and continue on, base-forward, for quite some distance.)
4) Muzzle blast (both noise and flash) out of a 16" carbine, even unsuppressed, is dramatically less for the Whisper than it is for any of the common 5.56 defense loads. This can be important in an enclosed, darkened room.
Discuss amongst yourselves...