HK LEM trigger technical question

[Ron3]

First of all let me state I understand how a passive firing pin disconnector works and that the HK P30SK has such a system.

But I have a few other questions:

After working the action the LEM hammer spring is compressed and the hammer is down.

What is "down" as far as the hammer itself? 0% cocked? 30%?

Is the main spring disconnected from the hammer at any time? I'm guessing no.

Is the mechanism designed so after the slide is worked, the main spring is about 90% compressed, hammer is where it is, and then pulling the trigger both fully compresses the mainspring and draws the hammer fully back before dropping it?

After working the slide does anything secure the hammer in place? Just the sear?

[HKGuns]

I only have a single HK LEM pistol. I did the conversion myself, but it was a while ago, so I don’t remember much about it.

Hammer down is hammer down, that is about the extent of what I can tell you technically.

There are a bunch of HK armorers over on HKPro where you are likely to get a better response.

[JimmyB62]

The LEM has a separate cocking piece which stays 100% cocked when cycled. The hammer may be down but the cocking piece is cocked. It’s a bit like a two piece hammer. It’s very different from a standard da/sa hammer. If you install one in a gun with the rear decocker, you can still use the decocker to decock the cocking piece even though the hammer is down.

[Eliakim]

First of all let me state I understand how a passive firing pin disconnector works and that the HK P30SK has such a system.

But I have a few other questions:

After working the action the LEM hammer spring is compressed and the hammer is down.

What is "down" as far as the hammer itself? 0% cocked? 30%?

Is the main spring disconnected from the hammer at any time? I'm guessing no.

Is the mechanism designed so after the slide is worked, the main spring is about 90% compressed, hammer is where it is, and then pulling the trigger both fully compresses the mainspring and draws the hammer fully back before dropping it?

After working the slide does anything secure the hammer in place? Just the sear?

I've done a couple of LEM conversions from TDA (HK45C & P30) a few years ago. I'll answer as best I can remember

1) Depending on variation of LEM the hammer in normal LEM is almost all the way down and held away from touching the firing pin by a steel lever called the "catch" when the pistol is cocked but finger is off the trigger. In the LEM 4.1 the 4.1 hammer is held farther away, perhaps 30% cocked by the 4.1 catch.

2) In LEM the hammer spring rod bears on the cocking piece, not the hammer. So the answer is yes.

3) When the LEM is cocked the mainspring is fully cocked. Pulling the trigger brings the hammer fully back and is released when the "release catch" (sear) is tripped by pulling the trigger to the rear.

4) When the LEM is cocked the hammer is held forward against the trigger bar by a light torsion spring called the "elbow spring for hammer". The force of the mainspring easily overcomes the low force of the elbow spring.

For me, the trigger pull of an LEM felt kind of strange and unnatural first time I tried one. Also the first one I tried was a heavy LEM with about an 8 pound pull. The Light LEM brings the pull down to 5 1/2 to 6 pounds or so. If you play with springs you can get an LEM down ever further to 4 1/2 pounds without going too light on the hammer spring so you don't end up with light firing pin strikes messing up the pistol's reliability.

The LEM 4.1 was a Swiss police variation that slightly shortens the trigger pull but doesn't really change the trigger reset distance.


As far as keeping the decocker goes, I did that on my P30 and screwed up a match target with an unexpected flyer when I accidently hit the decocker and suddenly had a 10# pull instead of the 5# pull I was expecting. I changed out the decocker with an LEM catch after that and solved my problem.

Overall I like the LEM trigger for carry. Its nice to holster a pistol with my thumb on the hammer so I know I wont get a hole in my leg

[pag23]

I would reach out to Marine0303 on HKPro....James knows his stuff

[Ron3]

Thanks!