Shrapnel & Ingwe: I have been a many decades long user of H 335 and have shot countless thousands of handmade cartridges that were made with it - knock on wood - to date I have had no issues with it - just great accuracy and consistent velocities (according to my Oehler chronograph).
I must add that "I" am a notorious non-hotrodder when it comes to my handloads - I have NEVER loaded a single centerfire cartridge "above" book maximums, since I began handloading 63 years ago.

I also am so happy the O/P was not injured.
Hold into the wind
VarmintGuy