When I go to the shooting range, I collect shells that I either don't have or have not seen before. I was just looking through them, and found one that I have no clue what it is. I will describe it and see if anyone could possibly figure out what it is.

The case is just slightly less in diameter than the .223 Remington, is .22 cal. and appears to be military. The letters and number on the head stamp are L C 53. The length is approx. 1 9/16". The neck is slightly longer than the .223's and the shoulder is not quite as steep.

Has anybody seen this cartridge before? I sure haven't, but would like to find out what it is just to fill my curiosity. Any help would be great, Thank you!