I just got a new 458 Socom about two months ago. I knew going in this was a "reload" only type of caliber and I reload so no problems there. Certain times of the year it seems 458 SC ammo becomes impossible to find as cases are made once a year and there are only a handful of "Factory" ammo makers, period. That being said ALL gas systems will not work with ALL ammo. My first outing I used some SBR factory ammo. Shot fine, did not cycle the action at all. I have a mid-length gas system and this has proven to work with only certain types of powders such as IMR 4198 and my favorite, Reloader 7. Once I pulled those bullets and used RL7 it worked great.
This video shows the weak ejection caused by the use of powder such as H110.
This one shows the good ejection using RL7 powder.
I like it, it's a hammer for sure, and it fits in an AR platform.