I took another crack with these on the .458SOCOM and I'm sorry to say the results were not good. I went through all 10 again and had the same problems as I did the first time around - jambs and misfeeds
I ran a few more through the STAG with no problems so I'm figuring at this time it must be related to the .458 specifically. Unfortunately I have about 40 Pmags for the STAG so I don't need the Cammengas as well.
If anybody is interested I'll trade my 10 for some mil surp or C mags that I can use in my .458, just shoot me a pm.