New gun with new conversion kit + mid power ammo= I am not surprised.
New gun should not be a huge issue but it would not hurt to fire a couple hundred rounds of 5.56 which might slick up the trigger group some .
Op handles come different dimensions and materials , some don't play well with conversion kits.
I have had best results by using a dry lube or silicone on conversion than oil. Oil just seems to slow things down and gum things up . Doesn't hurt to take conversion apart and buff it a bit with steel wool or a nylon scotch brite pad to slick up the rails a bit.
If you can come up with full power mini mags it should help break in the conversion .
Some times ejection problems with conversion kits are a symptom of the magazine lips dragging on the bolt. To check this chamber a round , remove the mag , then fire and see if the conversion ejects the single round . Sometimes the fix is as simple as taking the mag and taking a couple of strokes across the top of the feed lips but care should be taken as too heavy a file hand can muck up the mag.
Mark your mags and try to track them to see if your problems happen more often with a particular magazine.
Buffer should be pressing against rear of conversion when gun is closed up , stick something in there to be sure if you can't tell .
Some guns take a particular conversion and run well from the get go , some are a PITA . Keep with it , when you get it worked out they are a real joy to play and train with