I have been building two lowers in my spare time, just to see how well I can do. Maybe not so good. I have a common 2 parts, with both, that I can't identify. Hoping the ODT wisdom can help. Both lowers are from different manufacturers, and were stripped when purchased. These two parts, though, were spit out when attempting to add the stock/buffer tube/spring assembly. I don't know which parts they came from. One is a very short spring, the other a rubber pin of the same length that goes inside. Both receivers seem to work fine without. What am I missing?
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