Improving the Marushin XM177E2 firing performance

Sorry I do not get time to post much, but I know a lot of people have "issues" with the firing performance of the XM177E2, so I though I would share my own experiencies, bit rushed so please excuse typos:)
Please note, all the following tips were sourced via looking at Lucifers work and hours spent on google!!

My Model:


Main problems are feeding, Jams and misfires:

Feeding cure (for me):
Once usual mag feed lips smoothed etc sorted, I still had problems, this is how I sorted it, as the bolt goes forwards over the mag it can "jump" upwards slightly, also a problem on return stroke as slight jump "spoils" extraction.
Cure to fit the following peice of steel to maintain bolt level during cycling:

another angle:



Next Jams:
All My jamming problems were caused by standard extractor set up, notice that after very few rounds the extractor began to "bend" away, outwards, from its correct position, Also it had movement, The extractor should have NO "sideways" movement at all, only vertical.
Given the space the extractor sits in is larger than the extractor movement is bound to happen:(
Jamming Cure:
Old extractor was binned, and I made a steel one. In the photo below you can see a small "pin" through the bolt dirrecly over the extractor, this is a threaded brass screw inserted from the inside that allows me to "adjust"/ prevent any outwards movement of the new extractor, thus macking sure it only moves up and down, and not outwards.

another angle:


Misfires:
The misfires were caused by two factors,
1 Pins in botom of carts were sometimes short on some carts, Cure was to insert .5mm washer behind detonator pin, which means this is no longer an issue as det pin now allows for these shorter cart base pins.

2 "Firing pin" / firing "bar" can float around in its channel too much.
Cure insert a small "shim" between bar and bolt where indicated below, this stops bar floating up on firing.


With this all done the model will rip though full mags without any issues
However top receiver wobble really bugged me so fitted part shown below and now all sits snug and tight with no wobble at all


What was a frustrating model is now a delight!!

Well sorry that was a bit rushed but hey tried my best

Excellent mods as it's one of the best looking modelguns around it's a shame it has so many problems

8ace

Excellent John , it's really good to have this type of post submitted by members.

Marushin's XM177 / M16 series have always been plagued by firing problems much to owners' dissappointment. (Myself included )

Thank you very much for this detailed cure, it'll be of great use to us all without a doubt

Hello John

Can you tell us what the thickness of the little metal plate is that you screwed on top of the bolt?

The way you have solved the problem of the extractor is excellent, but I did it this way (see second page):
https://mp40modelguns.forumotion.net/modelgun-problems-f5/m16-bolt-problem-t1779-15.htm
It also works. All of the carts are extracted perfectly and I think it is much less work

You think I can also reduce the wobble on my M16A1 the way you did it with your XM177E2?

Hi Yellow:)
Agreed a lot easier!! I unfortunatly copied the extractor exactly when I made it in steel, if I had of thought it through I would have made it thicker so not packing needed but made the extractor before noticed the "wobble" just to replace bent one.
Peice of metal is just thick enough to provide clearance for charging handel stem ( I will measure over next few days, but made it "to fit" by eye
BTW thanks I remember it was your post that gave me the idea about shim under firing bar!

Thanks for taking time to share this with us :-D
I wish I had skills to invent such things, great job here!