Hello Forum,
I am considering buying a MP40 and going the SBR route. I have watched a few YouTube videos about a few reliability issues, and I am wondering if there is a thread on this subject. I used this forum for my GSG MP5 clone, and after making the modifications I read about on this forum, my carbine runs! I am hoping to do the same with the MP40. Can someone please point me in the right direction? Thanks!

I don’t know of any other forum covering the ATI MP40 as much as here and this is the only place I’ve seen the SBR kit discussed.

I’ve only got about 250 rounds thru mine, mostly cheap Blazer brass 115 gr. but no problems, not even a misfeed.

The only issues I’ve read about are charging handles flying out under recoil, rear sights coming off, and loose screws on the body halves.

Mine has none of these other than a few of my body/receiver screws needed a bit more tightening but nothing working loose.

I have been watching some YouTube videos, they mention a few issues.

The spring that works the magazine release is weak. If you increase the strength of the spring, the mag locks tighter in the mag well, and this makes the pistol more reliable. No magazine cocking forward or backward while you hold the magazine while you shoot.

The spring that holds the cocking handle in the bolt is weak. There are a number of fixes, you just have to decide how you want to deal with this issue. Weld the cocking handle to the bolt, add washers, or get a new 1911 spring, and cut coils off until you are happy.

The screws for the rear sight can work loose. Locktite is the simple fix.

The trigger bar is to long. A few fixes, it really depends on how involved you are willing to go. Buy a new one, or add a spacer.

There may be more, I was hoping there was a page in the Armory for the MP40. A page that described all of the problems, and the fixes. I did go through my MP5 clone, and it is very reliable now. Same with my StG 44, a few issues, fixed, and now runs great.