Mid-length gas system in the cold.

[Disciple]

Split from another thread:

middies blow in the cold and will choke in sub freezing temps unless you open them up negating the the 'supposed benefit' of the middy. I say supposed because Crane testing was immaterial. Dissy has the rifle length for longer sight picture before dots were a thing. Has nothing to do with someone needing long arms

Trying to figure out the basis of this statement I found https://partner-mco-archive.s3.amazo...1527866983.pdf which I suppose is or is related to the Crane testing that was dismissed as "immaterial." Why is it so? It shows less malfunctions with a mid-length gas system than with a carbine-length gas system at low temperatures. At the same time a reduced cyclic rate was observed. Are there conflicting reports?

- 960 rounds at -60F for Reliability at Low Temp

-For carbine-length weapons, 27 out of 65 malfunctions occurred during low temperature testing. For
mid-length weapons, 16 out of 30 malfunctions occurred during low temperature testing. For low
temperature testing, carbine-length weapons had 333.3 mean rounds between failures (MRBF) compared
to 836.1 MRBF for ambient temperature testing and mid-length weapons had 562.5 MRBF compared to
1993.8 MRBF for ambient temperature testing. Approximately half of the total malfunctions recorded for
both carbine-length and mid-length weapons occurred during low temperature testing, so the relative rate
of malfunctions between carbine-length and mid-length remained similar to that of ambient temperature
testing.

- Averaged overall bolt speeds and differences in bolt speeds are presented in Table. The P-Values of
bolt speed results for both suppressed and unsuppressed fire are less than 0.05, so there is a statistically
significant difference between the two gas systems. Bolt speed is uniformly lower for mid-length gas
systems when compared to carbine-length gas systems. Mid length bolt speed was 2.13 fps, or 12.4%,
lower than carbine-length for suppressed fire and 3.23 fps, or 22.6%, lower for unsuppressed fire.