Why does my ar 15 have light trigger strikes?

just built my ar, shot 40 rounds with no problem. Used american eagle. Then used federal and had light trigger strikes on alot of rounds, and tried them later on and some would fire. Brand new everything. I dont understand why. At first my pins were walking out, but every shot that I would shoot i would make sure they were even, and it would still have a light primer strike. Some would shoot no problem, but had alot that didnt. Any ideas?
here is a picture of my lower. Does it look right?


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