I'm far more familiar with the Stoner pattern weapons than Ingrams. I will have to agree to disagree. I've had a few rounds over the years that I was shocked did NOT explode.
I have also seen someone stack TEN rounds in a Colt AR-15 Sp-1 barrel, prior to splitting it like a wicker lantern on the 11th. (He was manually cycling rounds after a squib, thinking it was an ejection issue.) This barrel was on display in a gun store in Florida for almost 20 years. The dealer kept to show people how dangerous not knowing what you are doing can be. The "operator" had two fingers nearly severed when the barrel finally popped.
Regardless, even a faint chance is concerning over 10s of 1000s of rds.