I remembered having tried a Sprinco 5-coil at some point, and when I went to look for it in the parts box just now, I found that I had one of their 4-coils as well. So I measured….
Colt copper-washed: wire diameter .026, ends ground, approx 3-1/2 turns by my count. Free height ~.175
Sprinco 5-coil: wire diameter .025, ends not ground, approx 4-1/2 turns. Free height ~.225
Sprinco 4-coil: wire diameter .026, ends ground, approx 4 turns. Free height ~.190
Damage Industries copper-washed: same measurements as Sprinco 4-coil.
Old-style from unknown mfg: wire diameter .022, approx 3-3/4 turns, ends ground. Free height ~.160
ETA: I’m glad I did this because until now I had assumed that the Damage Industries spring was the same as Colt’s. Not quite.
Last edited by Curlew; 02-08-22 at 16:55.
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Both springs are recommended by some reputable SME's.
But statistically, the Colt spring is more proven having been in use by the military's current production M4's since 2003.
Last edited by prepare; 02-09-22 at 04:08.
You won't outvote the corruption.
Sic Semper Tyrannis
How many cycles is the Colt spring rated for?
You won't outvote the corruption.
Sic Semper Tyrannis
I don't think is required to be "rated" for anything. The only thing it is required to to do is go 6,000 rounds without failing.
However, I do know of one test where 20 M4s shot 720,000 rounds, and wound up replacing 4 extractor springs, total. It was not in the top ten items replaced, by the way.
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