Another mod and review post about the GSG MP40. Finally got around to working on it again and scooped up some MFI parts.

First, this thing is nothing more than a range toy or zhe German LARPing gun, and that is ok! Barring a powerball win, it’s the closest most of us will ever get to the feel of an MP40 (or rent one I suppose). Plus, when your wife knows you love WWII guns, and she gets you an MP40 for your birthday, you say thanks and go shoot it.

Like most others have done, the trigger bar mod is an absolute must. Trigger pull on these is terribly long, spongy, and overall trash. I forget the exact length, just took a piece of stainless flat bar, drilled holes in each end so it eliminates over half the take-up. You’ll also need to mill or Dremel a spot for the retainer latch. Basically, copy the existing bar for that part. No pics of this, I did the mod a couple years ago and there are a bunch of screws I didn’t want to remove again.

I did the cut at the rear of the receiver to mimic how the originals looked and operated, it doesn’t take away any structural integrity; the rear of the receiver is encased in the lower frame ring. Its made of zamak or some kind of aluminum/zinc alloy (the pot metal hi-points are made of) so it cuts very easy. I used an 8mm carbide end mill but found it gummed and clogged up too quickly, so I switched to a 5mm and took lighter passes using the end instead of the side. You will need to stick something inside the receiver to add rigidity for gripping it in your mill vise. I used a couple parallel bars. There will be a bit of flex, take light cuts and you’ll be ok.



I suppose the most unique mod I did was to stamp the gun in the Wehrmacht fashion, all over the place. I have dirty bird stamps from doing K98 restorations, and some various letter sizes. I looked on duck duck go images for real MP40 markings and replicated. Not my best stamping job on the rear, it is kind of fragile material to be whacking with a hammer and punch. More, lighter hits are better than fewer, harder hits. The zamak stamps very easily, you will probably need to strike each character multiple times from different angles due to the curved surfaces. I also stamped an S at the safe notch.





As for MFI parts, I used the muzzle nut, sight hood, takedown screw, and charging handle.

The muzzle nut doesn’t interact with the plunger, I suppose I could cut a notch later. Looks way better than the factory one.
https://mfiap.com/i-23899885-gsg-mp40-9mm-only-muzzle-nut-thread-protector-barrel-nut-wwii-period-correct-early-fine-groove-style-price-includes-sh-via-1st-class-usps-insurance.html

Sight hood looks WAY better and authentic and is very easy to install. Just watch the front sight will probably slide out of its dovetail.
https://mfiap.com/i-23899918-mfi-replacement-wwii-period-correct-front-sight-hood-for-the-gsg-ati-mp-40-mp40-mp38-price-includes-sh-via-1st-class-usps-insurance.html

The takedown screw is very nice, a long Chicago screw using two flat heads is far superior to the idiot C-clip thing you lose every time.
https://mfiap.com/i-23900026-mfi-improved-wwii-style-takedown-take-down-pin-for-the-ati-gsg-mp40-price-includes-usps-ground-select-8-75-off-if-ordering-with-any-other-product-with-sh-included.html

The charging handle is a must for authenticity and feel, plus there is no way it will fall out during shooting, which is a huge problem with the factory one. Mine does take a bit of fitting to lock it up into the safe notch, will be easy enough with a file after working it a few times to see the wear spots.
https://mfiap.com/i-23900013-mfi-gsg-mp40-9mm-cocking-handle-charging-handle-wwii-period-correct-price-includes-sh-via-1st-class-usps-insurance.html

I did not get the safety disc, I will though. Must have forgot to add to cart but I’ll say it will be added next parts order.
https://mfiap.com/i-23900027-mfi-gsg-mp40-9mm-22-lr-disk-safety-wwii-period-correct-price-includes-sh-via-1st-class-usps-insurance.html

I did SBR mine with the ATI stock, it might need some adjustment because my angle is not quite right. I saw another thread showing the more downward angle, whereas mine is more straight or even upwards. SBR trust engraving was also done with hand stamps, because why not. I was able to bump fire it a couple times, it’s a pretty fun blaster!