How does hk mp5 work

These guns used steel rollers locked into the barrel extension. It utilized a gas-operated roller-locked breech similar to the MG This unexpected phenomenon gave Dr. Thus the Gerat 06H later the StG 45 chambered in 7. Like their later cousin, the MP5, these guns fire from a closed bolt using what came to be called roller-delay. The rollers force the angled portion of the bolt assembly, paradoxically called the locking-piece , rearward.

This piece must drive the entire bolt and bolt carrier against spring pressure before the bolt head can fully cycle, which gives a substantial delay. The delay allows gas pressure to fall to safe levels prior case extraction and ejection. To further enhance the reliability, many roller-delayed firearms also use a fluted chamber to assist with case extraction under higher than normal pressure.

This system allowed the CETME a straightforward sheet metal construction without complex machining that could fire full-powered 7. The action is left largely unchanged aside from locking-piece angle modifications to accommodate the change in cyclic rate and operating pressure. Compared to the previously mentioned open bolt blowback SMGs, the MP5 and its many variants have mild recoil, a lightweight, relatively simple sheet metal construction, and superb accuracy. Very little has changed in the intervening years, and it does have some of the drawbacks that one would expect from its age.

The MP5s and its variants generally do not have a last round bolt hold open, provide little real estate for attachments, and have outdated, though manageable, ergonomics, according to Josh and Henry of 9-Hole Reviews. If you have the chance to fire one, you will see why. Patent Office, drawing by Theodore Koch All information in this article is taken from Forgottenweapons. Unlocking See illustration 47B below. In the course of the rearward movement of the bolt group the cartridge case is pushed from the chamber of the weapon by residual gas pressure.

The cartridge case is held securely in place on the holt head by the extractor until the front tip of the ejector strikes the rim of the cartridge case as the bolt recoils rearward. The front end of the ejector is pivoted up into position through the bottom of the bolt head to strike the cartridge case as a result of the rear of the ejector being pushed down by the recoiling bolt carrier.

At that moment the case is propelled from the weapon through the open ejection port. As the bolt group travels rearward energy is stored in the recoil spring as it is compressed by the bolt group. At the same time the hammer is depressed to a point where it can be retained by the sear or catch. Once the bolt has reached it's rearward most position, it begins it's forward travel as a result of the energy stored in the compressed recoil spring.

As the bolt nears the magazine, the ejector spring that was compressed during the ejection stage now forces the rear of the ejector up and the front of the ejector down and out of the way of the bolt group. If a cartridge is present in the magazine the compressed magazine spring will lift the cartridge into a position under the magazine lips.

The lower portion of the bolt head drives the cartridge from the magazine, reeding. In the 9mm MP5, when the magazine is empty, the bolt travels forward over the magazine follower. In the 10mm and. The cartridge, pushed from the magazine by the bolt group, is directed into the open chamber. Chambering As the cartridge assumes a horizontal position during feeding the rim of the cartridge cases snaps in under the lip of the extractor and is therefore held securely in place on the face of the bolt head.

As the front edge of the cartridge case makes contact with the shoulder in the chamber the face of the bolt head contacts the rear of the chamber which stops it's forward movement. The bolt carrier, however, is still free to move forward as a result of the gap that exists between it and the bold head. The forward movement of the bolt carrier pushes the locking piece through the bolt head. The angles located on the front shoulders of the locking piece force the locking rollers into the locking recesses in the barrel extension.

The safety axle blocks the movement of the trigger which in turn prevents the sear from being disengaged from the sear notch located in the hammer. The hammer is held rearward in a cocked position by the engagement of the front top corner of the sear in the rearmost notch sear notch of the hammer.

The hammer spring is compressed on the hammer strut. The rear end of the sear rests on the top shelf of the trigger. The sear is held rearward by the hammer spring through the hammer and upward by the elbow spring. As the trigger is pulled a notch located in the rear extension of the trigger passes into a cut out in the safety axle.

This cut out allows for sufficient depression of the front of the sear. The sear disengages from the sear notch on the hammer. The hammer begins to rotate on it's axis to strike the firing pin due to the energy stored in the compressed hammer spring. Simultaneously, the sear spring pushes the sear forward. As it does the rear end of the sear drops down onto the lower shelf on the trigger thus raising the front top corner of the sear into a position where it can engage the hammer as it is recocked by the bolt group.

As the bolt travels forward the hammer is held in a cocked position by the engagement of the sear in the sear notch on the hammer. Once the trigger is released, the hammer presses rearward on the sear against the weaker sear spring which causes the rear end of the sear to reset on the top shelf of the trigger. The trigger mechanism is now ready to release the hammer to fire the next round with the next squeeze of the trigger. This allows the trigger to be pulled further to the rsar than in the semiautomatic mode.

This drops the front top corner of the- sear below the point where the hammer can reengage it as it is recocked, even when the rear end of the sear jumps down onto the lower shelf on the trigger.

At this point when the bolt group travels forward the hammer is not held rearward by the sear. It is momentarily held rearward by the engagement of the catch in the forward most notch catch notch in the hammer. The hammer will be held in that cocked position until the release lever is depressed by the forward moving bolt carrier. Once the bolt group is fully locked the release lever has been depressed to the point where the catch is pressed forward and disengages from the catch notch in the hammer.

The hammer is then automatically free to strike the firing pin and fire the weapon. This process continues until the trigger is released or the magazine is emptied. If the trigger is released the sear is repositioned to reengage in the sear notch, as described above in the description of the semiautomatic mode of fire, and firing is interrupted.

This toothed count wheel will hold the sear out of engagement with the hammer for the total number of rounds in the burst provided the operator holds the trigger rearward long enough for all rounds to fire.