I'll contribute to this thread some more.
After I sold my beloved DTI (aka Delton) to a good friend (I was getting a LMT) it has never had a single malfunction with me.
Even the Tula Ammo which is almost all he shoots has done veyr well.
I think he has had 2 cases where the Tula failed to cycle the bolt fully back into battery but I think we can all agree thats an Ammo issue since the Tula is well know be loaded a bit soft, with some rounds occasionally very soft.
I doubt even my $2300 LWRC's would fully cycle Tula all the time.