Various .22lr cartridges Firearm : Ruger 10/22 rifle with 18.5" barrel length. Calibration : 10.0 ± 0.05cm and 587 ± 0.500 ft/sec impact velocity. Impact velocities were not taken of the bullets, due to the indoor lighting present at the test area. The block was calibrated 1 hour prior to the test (in the outdoors) and returned to quasi-steady thermal equilibrium in a refrigerated space prior to the firearm test event. Velocities and performance obtained should be typical of .22lr rifles. Shot 1 - Aguila Sniper SubSonic 60 grain lead bullet. Penetrated the block head-on until ~ 7" when the bullet flipped unto its side. At this point the maximum permanent cavity was 0.5" until ~ 10" penetration depth, when the bullet turned either point-forward or base-forward and exited the back of the block at 16" penetration depth. Bullet was not recovered. Shot 2 - Aguila SE 38 grain lead hollowpoint. Penetrated to 10.5" with expanded diameter of 0.344". Shot 3 - CCI Velocitor 40 grain Gold Dot bullet. Penetrated to 13.3" with expanded diameter of 0.335". Shot 4 - Federal 36 grain Copper Plated Hollow Point. Penetrated to 14.3" with expanded diameter of 0.308". Shot 5 - CCI Quik-Shok 32 grain pre-fragmented bullet. Fragments penetrated to 5.5", 5.4", 6.3". Shot 6 - Remington '22 Golden Bullet' 36 grain plated hollowpoint. Penetrated 11.9" and expanded to 0.340" diameter. Shot 7 - CCI Mini-Mag 36 grain hollowpoint. Penetrated to 10.6" and expanded to 0.302" diameter.