These things are not overly complicated,... If it is sticking in the chamber it is either:
1)extractor issue
2) chamber issue
3) oversprung
Extractor as previously mentioned can be checked eaisily. It was likely never fitted or tuned
Chamber issue, Sam chambers are horribly done. If it is indeed rough, finish reamer will fix easilly. If you can easily remove an already fired case with your fingernail or even gravity drop then chamber is loose enough. I have seen a few that were severly short chambered.
Oversprung, To strong a recoil spring and more often main spring to heavy can really mess with the timing of the whole process.
Rare but have seen it a couple times has been barrel lug fittment. both upper and lower lug and link have been wrongly fitted. If barrel is being pulled down to soon case can have an extractor over-ride the rim.
My money is on the extractor.
Magazine has no bearing whatsoever on extraction/ejection process