Posted: 5/4/2008 3:43:36 PM EDT
I surprised to hear the o-ring would be a deficient solution, since BCM threw in one for free with my purchase of one of their bolts. No one has said a bad word about them.
Anyhow, do you just put the o-ring down and re-install the extractor...compressing it all down? The o-ring didn't seem to fit over the spring (with blue insert).
Posted: 5/4/2008 5:17:48 PM EDT
[Last Edit: 5/4/2008 5:30:12 PM EDT by Ekie]
This is a extractor guide for OEM, USGI, Colt, FN, etc, has nothing to do with cheapo look alike parts.
The extractor buffer is a buffer for the extractor spring. It is not a color coded spring identifier, that is why it is called a buffer rather then a color coded spring identifier. The original idea was to extend extractor spring life. For example, in December of 1965 a lot of 4,800 rifles was almost rejected because one had a extractor spring break during a endurance test (508 RFW-122).
From left to right:
original spring 1959-1971
white buffer 1972-??
red buffer ??-1982
blue A2 buffer 1982-1993 or so
black buffer 1994-current (still in use on M16A3 and A4)
black buffer with M4 gold spring 2003-current
Extractor springs are the same for USGI rifles/Carbines other then the original spring, and the new M4 gold spring.
The black buffer is demonstratively stiffer then a black one. Here is a blue A2 buffer compared to a black one:
Pic by CJan_NH.
Here are some measurements I took with my trigger pull gauge. This is what the gauge read for the weight needed to get the extractor fully extended:
long spring, no buffer:
Black buffer used on M4's, and the M16A4:
3.5 lbs (well worn M4A1)
4.0 lbs (brand new M16A4)
2.25 lbs (well worn M4A1)
Black buffer, with gold spring as used on late M4's:
could not get a good reading, kinda stiff ya know, well over 5.0 lbs
Black buffer, with standard spring, and SOPMOD O-Ring:
could not get a good reading, well over 7 lbs on a well worn M4A1
These are not real scientific, too small a sample. There is some debate in regards to when the blue buffer was introduced.
In regards to the SOPMOD bolt upgrade kit, this was a Band-Aid for the old M4A1 extractor set up, that is the black buffer and silver spring. Due to the location of the gas port on the M4/A1 some of them had extraction problems (had one myself). Colt's had developed the specific gold spring and black buffer for the M4/A1 to address this, but the Big Army did not want to add another part to the system (gold spring). So SOPMOD came out with the doughnut to fix it. Since then Big Army has approved Colt's gold spring set up, and M4/A1's are now delivered with them, and I would not think the SOPMOD kit is needed on these.