Apologize for the simplistic question -- I'm more of a long range guy so this is a different animal.

My SR15 lower (Mod 2, carbine-length) with 11.5"/14.5" uppers is nearing 5K rounds. So, I figure it is time to swap the buffer spring. I'm running the KAC 21057 buffer. I shoot >90% MK 262 Mod 0/1, 77gr.--all unsuppressed (for a while longer). I'm currently ejecting brass between 2:00-3:00. The different upper BCGs are sharing wear, so I don't suspect ejector/extractor wear.

KAC doesn't build buffer springs, otherwise I'd just get one from them.

What spring would run 100% across the two uppers and keep that KAC smoothness for cycling? Searching the site seems to show favorites between Sprinco Blue, Colt M4 Carbine, and Tubbs flatwire.

Thanks