KAC SR15 Mod 2, 11.5" buffer spring replacement

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08-26-20, 09:57
CubeWarrior

KAC SR15 Mod 2, 11.5" buffer spring replacement

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
08-26-20, 14:27
R0CKETMAN

KAC SR15 Mod 2, 11.5" buffer spring replacement

I’m running a blue in my unsuppressed mod 2 14.5

KAC H2 buff
08-26-20, 16:47
CubeWarrior

Thanks-- I'll order a blue and move forward with it.
08-26-20, 18:45
R0CKETMAN

Quote:

Originally Posted by CubeWarrior

Thanks-- I'll order a blue and move forward with it.

Noticeable vs a new carbine spring. 3-330 ejection. Weakest I use is federal 223
09-06-20, 22:50
CubeWarrior

Thr Sprinco blue grouped a nice brass pile 6’ away @ 4:30. Worked great with both uppers. Thanks
09-07-20, 17:46
3 AE

Did you happen to measure the length of the buffer spring that you replaced? Curious to know what it was at around 5000 rounds.
09-08-20, 12:58
CubeWarrior

Quote:

Originally Posted by 3 AE

Did you happen to measure the length of the buffer spring that you replaced? Curious to know what it was at around 5000 rounds.

Its between an 1/8" and 3/16" shorter than my spring on my HD which only has a few hundred rounds on it.