Ran into a strange problem with my converted 10/22 to 17HMR. Never went to the range this time of year -- way too hot and humidity close to 90 percent. The sky was clear and I set the two boxes of CCI 17HMR TNT ammo out in the sun on the shooting bench. By accident, I had torn the label off the first box and it left a white paper backing on the top of the box -- the second had the dark TNT label intact. First box shot just great, no problems and very accurate. Went to the second box and started having problems right away -- very inaccurate and rims poping. I put the rifle and ammo away so I could shoot another rifle. After about 45 minutes I went back to shoot the 10/22 to see if I could figure out what happened and the ammo from that 2nd box now shoot just great -- very accurate and no blown rims!!! All I can figure is the heat from the direct sun must have affected the powder -- it had sat out in the sun for at least 30 minutes with that black labeled top closed over the ammo! I need to remember to keep my ammo out of the sun.Has any one seen a link, story etc. regarding KBs happening with 10/17s, by VQ, Magnum Research, converted Rugers etc. or is it just the Remingtons that were doing it?