dweste...I paid about $180 for the drop in conversion and magazine and another $25 for an additional magazine...I don't know your background with shooting sports, but I compete in a sport called 3 gun.. go to YouTube... Ft Benning 3 gun 2009 stage VII, and look at the video with Mike Darby, Kurt Miller et al...then go to Viking Tactics by Kyle Lamb and look at the video called "Highsmith Rifle Drill" and "9 hole rifle drill" and "three little kittens" the practice to accomplish and maintain these skills can be pricey at $.25 a shot... hence the .22lr conversion

you can purchase a second hand Ruger 10/22 for less than what the conversion will cost you and end up with a much more accurate rifle

If you want to continue your research on the .223/5.56 look at the recent ballistic gel tests (FBI) used to approximate animal tissue... when the velocity of the bullet is above about 2700feet per second, (depending on bullet weight) at 200m or less, the bullet will yaw 90 degrees and break apart the the cannelure (the groove on the bullet the case is crimped into ),and the resulting fragments will shred the temporary stretch cavity caused by the hydrostatic shock of the projectile impact producing a devastating wound....at velocities less than this the projectile will rotate 180 degrees, and leave base first (naturally depending on thickness of tissue and whether it strikes any bone... larger diameter bullets shot in non magnum .308 guns typically don't reach this velocity to yaw, drilling a caliber diameter hole, so hunting projectiles typically have a "hollow cavity" which allows them to mushroom to increase the the permanent stretch cavity producing a more humane kill. AS far a bullet yaw, a 3000fps bullet fired from a 1/9inch twist rate rifle is going 240,000rpm..(if my math is correct) and anything can cause it to deflect... regards Les