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Manufacturer
I read this
"Understanding Extractor Lift in the M16 Family of Weapons"
http://www.dtic.mil/ndia/2003smallarms/din.ppt
It explains that extractor lift occurs, but does not explain what causes it.
It says lift is not caused by "spin out", but occurs during the "initial rearward translation of the bolt after bolt rotation stops".
Any ideas what causes this?
Black River Tactical
BRT OPTIMUM Hammer Forged Chrome Lined Barrels - 11.5", 12.5", 14.5", 16"
BRT EZTUNE Preset Gas Tubes - PISTOL, CAR, MID, RIFLE
BRT Bolt Carrier Groups M4A1, M16 CHROME
BRT Covert Comps 5.56, 6X, 7.62
Senior Member
Where in the hell is IG when you need him.
"Air Force / Policeman / Fireman / Man of God / Friend of mine / R.I.P. Steve Lamy"
Senior Member
"Dual M4 High Fidelity Gymnasticator"I love it...
Industry Professional
Too much thinking going on there for me.
Originally Posted by Pappabear
Owner/Instructor at Semper Paratus Arms
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Member
Cliffs Notes - Use a stronger extractor spring...
Member
I read that same presentation a while back & wasn't all that impressed with the weak conclusion. It basically just points out when extractor lift happens. Kind of weak. And after an FTE Then this is their remedy:
"The ejector in the lower M4 was removed and the previous experiment was repeated. The unfired, lubed and primed case in the lower M4 extracted."
Oddly enough they kept the "remove your ejector" part out of their conclusions.
Senior Member
The whole presentation seems like an exercise to explain why they spent the time to build their gymnasticator. I don't even know where to start poking holes in their scientific method.
Member
When the bolt carrier and cam pin hit the bolt to start the rearward acceleration of the unlocked bolt it creates a very high acceleration load (perhaps 200,00 g’s) that gets transmitted to the extractor. The extractor bends like a spring under this load, but being a very brief impact load the extractor springs back to it’s original shape and springs away from the case. This dynamic motion causes the extractor to be out of position for the first .15 inches or so of case extraction. The only thing holding the case against the bolt face (while also keeping the ejector compressed) is the residual gas pressure in the bore. There is roughly 1,000 psi of gas pressure during initial case extraction.
The gymnasticator was used to duplicate the bolt and extractor dynamics without the bore pressure, just to provide additional evidence to verify this phenomenon.
Senior Member
Welcome to M4C. Interesting analysis.
The Second Amendment ACKNOWLEDGES our right to own and bear arms that are in common use that can be used for lawful purposes. The arms can be restricted ONLY if subject to historical analogue from the founding era or is dangerous (unsafe) AND unusual.
It's that simple.
Industry Professional
Almost 5 years old. Definitely in the Necropost Awards runner up category.
Owner/Instructor at Semper Paratus Arms
Facebook: https://www.facebook.com/SemperParatusArms/
Semper Paratus Arms AR15 Armorer Course http://www.semperparatusarms.com/cou...-registration/
M4C Misc. Training and Course Announcements- http://www.m4carbine.net/forumdisplay.php?f=141
Master Armorer/R&D at SIONICS Weapon Systems- http://sionicsweaponsystems.com
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