Prior to release of 1.22.1 Server Code on 6/5/2008, physical prims used as "bullets" for ranged weaponry were able to reliably collide with avatars at Velocity settings of up to 100 m/s (so long as the bullet was at least 2 meters long). Since 6/5/2008, collisions with avatars have not occurred in any reliable fashion whatsoever. In testing: --Firing a 'bullet prim' (0.050, 0.050, 2.000 x,y,z size) at 100 meters / second velocity will always reliably 'collide' with another prim that is not attached to an avatar. --Firing a 'bullet prim' (same size as above) at 40 meters / second will 90% reliably 'collide' with an attachment of targetable size and at least 0.25 meters thickness, but will NOT collide with an avatar. Any higher velocity will result in almost complete failure of the 'bullet prim' to collide with the attachment. -Firing a 'bullet prim' (same size as above) at 1-5 meters / second will reliably collide with an avatar-though this restricts such prims to a very, very short range. -Increasing the size of the 'bullet prim' to 2 x 2 x 2 meters and firing at 40 meters / second -does result in an improvement in collision detection ratio, but also results in significant knockback of the avatar and is STILL not 100% reliable. Increasing the velocity above 40 meters / second reduces the reliability of collision (at 100 meters / second, collision was detected roughly 20% of the time with even a 2 x 2 x 2 prim). This issue is quite significant to many weapon-builders and role-play / combat system builders who rely upon avatar-collisions from prims to register 'hit's' and 'damage' and has effectively reduced many of our ranged weapons to 'unusable' until the issue is fixed. As such, it is affecting thousands of users. For reproduction...simply script a prim to fire another-physical-prim at various velocities...and have it llShout when it detects a collision.