Marushin MP40 (abs) - lower receiver strip down

There are already excellent guides on how to strip down MP40 for most purposes.
For sake of completeness I stripped down lower receiver and took some pictures during the process.

Step 0
Further instructions are based on assumption that you have succesfully separated upper receiver from lower receiver, as described in other guides in this section.

Step 1
Remove side panels.
Start by extending stock.
Next find two screws at the left panel, one near front, one near back.
Unscrew them. Front crew is shorter than back screw.
Nuts are fixed in the left panel, they should not fall out :-)
Remove panels, store them out of way, together with screws.





Step 2
Remove pistol grip.
There are two screws underneath lowe receiver, in front of trigger guard.
Unscrew the smaller one to unlock the larger one.
Unscrew the larger screw.
Carefully separate pistol grip (with stock) from lower receiver.
Remove cap from back end of lower receiver.






Step 3
Remove trigger assembly.
This is easier to do than put it back inside ;-)
Start by removing two pins keeping everything inside to the lower receiver.
One smaller in the back is pivot point for trigger.
Another, larger, is near middle, it serves as another pivot point for sear.
Spring and pin that pushes trigger will probably fall around around that time ;-)
Remove it, making sure it does not "spring out" and damage something.
Now there are two major parts inside lower receiver.
There is a metal bracket at the front, and a group: trigger still linked with sear and trigger bar.
Remove metal bracket first. You will need to wiggle it carefully.
It should come out quite easily, though you might need to move trigger group around.
Next remove trigger group. You will need to wiggle it, move trigger and sear around a bit, but it should go out easily.







Step 4
Disassemble trigger group.
There are two pins, one holds sear, another trigger.
They might fall out by themselves before you get chance of removal - do not lose them.
Remember positions how it all goes together! It is easy with MP40, but it is essential step :-)





Step 5
Inspect and clean parts from dust/rust that might have accumulated on them.
Trigger, sear, pins and metal bracket should not rust, but trigger bar is definitely rust-prone.

Step 6
Reassembly follows in reverse order.
There are two main difficulties:
The first is to get trigger group and metal bracket back inside receiver in correct position.
The second it to put trigger spring/pin inside in a correct position.
Patience, patience, patience...

Initial photos show how I managed to put trigger group back.
The last photo is an example of incorrectly positioned trigger spring. "Head" did not get into hole in receiver.








(edit: updated photos, corrected descriptions)

Never seen the trigger bar removed and assembled that way , usually it is fitted and removed via the upper long hole ( the forward one of the two ) inside part of the lower receiver .

Also your trigger bar is assembled the wrong way as its supposed to have the letter G ( that is stamped upon it ) as shown below ( this is to allow it to pass into the lower receiver in the correct fashion )




nice work on the guide though.

DOC

Interesting point about the bar. I didn't notice "G" and do not remember if I just put it back the way it was, or maybe reversed it.

Need to check if it's easier to take it out using front slot, I might have missed the obvious solution ;-)

Excellent I'm really pleased to see this type of detailed Guide being posted up.

Thank you smootik, and to you too Doc for your additional advice. This will certainly be a valuable extension to the Basic Guides I'd put together.

More like this will be very, very welcome

DOC

Ahhhh, the job is definitely easier with a manual ;-D

DOC wrote:

Never seen the trigger bar removed and assembled that way , usually it is fitted and removed via the upper long hole ( the forward one of the two ) inside part of the lower receiver .

I disassembled it again to check trigger bar. One comment: it is NOT easy!
Trying to get trigger spring in place, while keeping side pins from falling out takes a lot of time and effort. Somehow the first time was easier ;-)

Why Marushin distinguishes left/right side is a bit of mystery for me. As far as I have measured, that piece is symmetrical. Might have missed something :-/

(photos and description will be added later to the main guide, as I have some additional observations)

Some pre-built MP40s I have seen a small piece of sticky tape to hold the sear pin in place .

Trigger spring is fitted with the section upside down and the spring /pin is inserted with some small needle nose pliers or tweezers .

DOC