Ordered some .224, 55 grain spitzer bullets from Sierra Bullets in Sedalia, Mo. When I got the order I noticed on the front of the box it was stated: Medium Velocity bullets. Having never seen this before I E mailed Sierra and asked them about the phraseology. I was informed that the bullet was not to be used for velocities over 3600 fps and the barrel twist was to be slower. None of my reloading manuals approaches 3600 fps in a 55 gr. Does anyone have an explanation for this?