"Lapua offers a subsonic 200 grain jacketed, rebated boat-tail, spitzer bullet that seems to defy all logic and subsonic knowledge. Uncoated an unlubricated it never sticks in a dirty bore. A stability factor of only 1.36 suggests it shouldn't stabilise from anything less than a 1:8 twist yet it works just fine in the more common 1:10 twist.
The only issue with this bullet is its minimal terminal performance. This thing will penetrate about 26 inches in wet paper and come out in good enough shape to be reloaded and used again."
"Expansion is the most difficult task for subsonics. The Lapua subsonic bullet appears to have a very thin guilding jacket, giving it the potential to deform more easily on impact. It doesn't expand but can bend and flatten depending on what it hits. FMJ-BT designs do not deform."
http://members.shaw.ca/cronhelm/SubsonicBullet.html