1. try different ammo. surplus light ball, commercial wolf, bear, PPU and S&B. try diferent bullet weights. low to heavy range.
2. stick to just one mag for not to introduce additional mag related issues. let's say use factory for now while you do some ammo testing. or better yet hand-feed until you find ammo that cycles well and ejects at least 2-3 feet.
once you find ammo that your rifle likes you can proceed with figuring out other issues. chances are with stout enough ammo one or two problems might go away on their own.
also it would not hurt to strip gun appart and inspect every single component in and out for undue wear. you never know when something might have been put together not in a good way.