operating cycle: help me understand

[rafaga]

Hi All,

I have no experience with the mg42 but am toying with the idea of a build in the future. Trying to learn as much as I can beforehand.

I'm curious about some details of the operating cycle.
1- What is the approximate length of the barrel stroke.
2- As it appears the barrel travels a short distance, does the recuperator return the barrel fully forward before the bolt comes back forward?
3- Is there a link to a clear explanation of the op cycle somewhere?

Thanks in advance for any help.

[DARIVS ARCHITECTVS]

The barrel moves back roughly 3/8".

The recuperator does return the barrel to the forward most position before the bolt cycles and begins it's forward movement again, picking up a new round in the process. if the barrel were in the rear position and the bolt in the forward position, the bolt would not lock into the barrel locking piece, because the cams of the camming piece would prevent the rollers from moving to the outboard, locking positions.

Ffolke Myrvang's book "MG34/42 Universal Machineguns" is the nest book out there and has details as to the full operating cycle. No self respecting MG-42 owner would be without it (except maybe Bil, who has enough trouble getting respect from us, much less himself ).

[rafaga]

Thanks for the info. I'll have to search out a copy of that book.

Just last night I was reading in an old Shotgun News about a predecessor to the MG34 called a Solothurn. That particular weapon did hold the barrel back with a latch until the bolt came forward again and into chamber. Then together they traveled the last little bit while the bolt rotated into battery. No recuperator in that weapon, it was all return spring. I believe the Browning M2 also holds the barrel back if I'm not mistaken.

If I understand the MG42 correctly, as soon as the cams move the rollers inward to disengage the locking piece the combination of inertia and blowback gases send the bolt rearward. At the exact same instant the recuperator returns the barrel forward against the barrel stop while the bolt is still flying rearward.

So that's why these things are so fast. WOW!

[Bil]

http://science.howstuffworks.com/machine-gun5.htm Doesn't get much better than this-click and hold on the trigger and the gun cycles.Next bage is subguns,same thing.Nice animations. ---bil

[JBaum]

The full operating details and function/troubleshooting of the MG42 is listed in pieces and parts of messages throughout this website.

Folke Myrvang's books is also good, but doesn't explain the operation in detail like reading the manuals that are available for the MG42. There are around 10 operation and repair manuals available in English for the MG42/MG3 series of MG.

[Boondoggle]

The MG42 also uses gas assist to operate. The recoil booster traps the muzzle gases so the front of the barrel acts as a piston to get the necessary power to force the rollers through the cam. Different size orifices in the booster can adjust the amount of gas assist to work with different power ammo, or tight vs worn parts.

[Boondoggle]

I believe the Browning M2 also holds the barrel back if I'm not mistaken.

So that's why these things are so fast. WOW!

Systems where the barrel travels the full distance with the bolt are called "long recoil", vs "short recoil" like the '42.

Many older MG's also pull the cartridge from the rear of the belt and drop it in front of the bolt as it travels forward. This requires the bolt to travel a greater distance that the MG42, which simply pushes the cartridge through the belt. This shorter bolt travel adds a great advantage to firing rate.

[42rocker]

Bil
That was a great link showing how it works.... I think that a lot of schools boards could be unhappy with that science project...

Later 42rocker

[Bil]

Maybe if it shot crayons instead of bullets... No,just mentioning something like this can get you suspended nowadays-the thought police are everywhere! ---bil

[Michael J]

http://science.howstuffworks.com/machine-gun5.htm Doesn't get much better than this-click and hold on the trigger and the gun cycles.Next bage is subguns,same thing.Nice animations. ---bil

Well, the real thing sure is nice ! Rafaga, any mg42 members around your area? Maybe they could take you to the range, or invite you over to show you the gun up close and cycle it dry

[rafaga]

Well, the real thing sure is nice ! Rafaga, any mg42 members around your area? Maybe they could take you to the range, or invite you over to show you the gun up close and cycle it dry

There is a guy here in central Texas that specializes in German militaria at the local gun shows. I'll chat with him at the next show.

[rafaga]

Maybe if it shot crayons instead of bullets... No,just mentioning something like this can get you suspended nowadays-the thought police are everywhere! ---bil

My teenage boy recently completed a mini rail gun project for a science project at school. He used parts from disposable cameras, AA batteries, wire, a gutted Bic ballpoint pen for the barrel, and remotely controlled it with a parts from a broken RC toy plane. It shot out pieces of straightened paperclip wire about 2 feet. The kids in class were enthralled. He got an A+.


God Bless Texas!!!!!