It's a poser! The only difference Coincraft shows between 5A & 5B are a filled in eye!!! The text claims that 5B has a narrower face but, even with a ruler, their examples are identical. Your coin shows the 'filled-in' eye but that may be wear. However Spinks seperates the two with A having a ball tail to the R and B having a wedge tail. On this division, your coin appears to be the latter, 5B. You pays your money and takes your choice! So I doubt you will ever be absolutely certain!