.30 Caliber failure to feed

[Bungalocity]

Hi there,
Today I got my 1920's DWM .30 like yours, and upon testing it in the range with Fiocchi ($30/50 as opposed to the Winchester $40/50) I went through 40 rounds with only one jam.

Like yours it was pointing upward about 45˚ into the chamber.
Had the range worker pull it out by hand, I wasn't going to touch it!
Left some knicks on the lead.

I hadn't oiled it or anything. The mag is aluminum and they seemed to think since it doesn't match anyway, it was a WWII later era.

So, maybe next time I'll try the Winchesters!
Good luck, hope you solve it all and let us know what you think it may be!

PS - I cannot recall the locking mechanism staying up after the clip was exhausted.