I'm sorry to say the rifle is not in original condition, the rear sight is gone as is the protective ears to guard it and the upper and lower wood hand guards are also gone , and the barrel has been cut to 20"
You say the rear sight protective ears are ground off; is the charger clip guide still in place? If so, you can find stripper clips and reload that rifle very quickly using stripper clips.
Any magazine alteration would merely be something else sticking out to hang up on stuff.
Hey Archie: I'm Not sure what a charger clip guide is, But if you can tell me how to post a pic I'll snap a shot of the top of the receiver if that helps at all