AR-15 platform

[Panman65]

Ive just signed on so greetings everybody. I was reading a question earlier about the difference between the A-2 buffer and spring, and the carbine length buffer and spring. Yesterday I was out test firing a new .223 Wylde carbine upper matched with an A-2 fixed stock with matching buffer and spring. The results ended in a .223 single shot. Duh. I've got a carbine length buffer, but should I use the buffer and matching spring? Or can I change out just buffers. This is my new hypothesis. Also, for .223, 5.56, and .300 aac overall case length should be 2.060" (+-.003) I've made some subsonic 230 gr lead bullets. My results are not all blackouts have the same headspace. Any takers?