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Posted: 3/28/2006 11:23:03 AM EDT
[Last Edit: 3/28/2006 11:25:45 AM EDT by Epsilon]
Ive been trying to understand exactly how the G3 and Mp5 systems work. I think I just about understand the roller locking and trigger system but one thing still has me scratching my head.

How does the charging handle not reciprocate with the bolt carrier?
Link Posted: 3/28/2006 11:28:06 AM EDT
The charging handle lug or what ever you want to call it is ahead of the bolt carrier so when the bolt carrier is moved to the rear the charging handle stays put.
Link Posted: 3/28/2006 11:32:37 AM EDT

The charging handle lug or what ever you want to call it is ahead of the bolt carrier so when the bolt carrier is moved to the rear the charging handle stays put.


But wouldnt the gas push it back along with bolt carrier?
Link Posted: 3/28/2006 11:39:51 AM EDT
There is no gas used in the MP5 roller locked action--just a push from the cartridge base on the bolt face. The charging handle is in front of the whole operation and not connected. So, you can push the whole assembly with the charging handle, but the action cannot pull the charging handle with it.

HTH
Link Posted: 3/28/2006 11:41:35 AM EDT
[Last Edit: 3/28/2006 12:05:42 PM EDT by FMD]
The bolt carrier has an extension that runs forward to the cocking tube.

The cocking tube has a slot and a small insert in front, but seperate from the bolt carrier.

When you pull the handle back, that insert pushes on the bolt carrier extension. When you let it fly forward, it says forward. Kind of like an AR CH, but out front.

ETA: Yep, no gas system. Essentially it's recoil operated (roller-locked delayed blowback).
Link Posted: 3/28/2006 12:10:51 PM EDT
Yep.
Link Posted: 3/28/2006 1:26:26 PM EDT
[There is no gas used in the MP5 roller locked action/quote]


Haha good point! I completely forgot that the roller system doesnt use gas!
Link Posted: 3/28/2006 7:53:51 PM EDT

Originally Posted By tank254:
There is no gas used in the MP5 roller locked action--just a push from the cartridge base on the bolt face.




Not exactly true. The cartridge pushing back during firing doesn't make the action cycle. Rather, it's the recoil impulse that causes the bolt carrier to move back and unlock the rollers and pull the bolt back.
Link Posted: 3/29/2006 2:02:56 PM EDT

Originally Posted By MP5_guy:

Originally Posted By tank254:
There is no gas used in the MP5 roller locked action--just a push from the cartridge base on the bolt face.




Not exactly true. The cartridge pushing back during firing doesn't make the action cycle. Rather, it's the recoil impulse that causes the bolt carrier to move back and unlock the rollers and pull the bolt back.




No, it IS the pressure of the cartridge base on the bolt face itself that forces the rollers back.

You have the concept backwards. The rollers are in the bolt, not the carrier, and it is the bolt and rollers that begin to move first. The bolt carrier doesn't "pull" anything. It is sometimes described as "delayed blowback" which is exactly what it is--the cartirdge pushes on the bolt face, which has to overcome the mechanical disadvantage of the leverage provided by the rollers in their recesses. They pop into the bolt and the bolt runs into the carrier and everything recoils back. The locking piece varies the force and timing, but the concept is the same from 9mm to 7.62.

What you are describing sounds closer to a Benelli autoloading shotgun's action, not an MP5.

HTH
Link Posted: 3/29/2006 5:49:24 PM EDT
I believe you are right. One must engage brain for typing...
Link Posted: 3/31/2006 10:44:50 AM EDT

Originally Posted By MP5_guy:
I believe you are right. One must engage brain for typing... hr


You, sir, are more of a man than most.


In all fairness the HK roller lock system is much more complex than it first appears. Witness the problems that the US clone market has in copying it and HK's abandonment of it for the straight blowback plastic junk that they now peddle.

Link Posted: 3/31/2006 10:51:09 AM EDT
[Last Edit: 3/31/2006 10:52:15 AM EDT by tank254]

double post
Link Posted: 4/1/2006 5:55:30 PM EDT
Along those same lines,
Why even have a cocking tube? Is it for alignment? Mass for the carrier? Left handed charging handle?
Seems to me all of these could be done cheaper and easier, seeing as there is no gas in there.

Why not chop off the whole thing and put on a right handed charging handle somehow mated to the (now shortened) carrier?
Link Posted: 4/1/2006 6:01:12 PM EDT
The cocking tube also serves the purpose of supporting the handguard, so that the barrel floats-an important consideration that helps the HK series to be more accurate. ARKAR
Link Posted: 4/2/2006 10:07:10 AM EDT
[Last Edit: 4/2/2006 10:07:54 AM EDT by nefariousnick]

Originally Posted By tank254:

Originally Posted By MP5_guy:
I believe you are right. One must engage brain for typing...



You, sir, are more of a man than most.


In all fairness the HK roller lock system is much more complex than it first appears. Witness the problems that the US clone market has in copying it and HK's abandonment of it for the straight blowback plastic junk that they now peddle.





+1
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