[Kent Frazier]

After reading the threads on the LEM conversions posted by Big Bore, I decided to convert my .45 Compact V1 (date code AB) to LEM.

If I understood the threads correctly, by keeping the V1 hammer spring and TRS I should have a trigger pull of around 5 pounds. I don't have a pull gauge, but the pull "feels" more than 5 pounds. I tried hanging a gallon of water from the trigger and this failed to "fire" the gun.

Do I need to change the Firing Pin Block spring? I remember seeing something in the trigger job thread about date codes later than AB. Could HK have changed FPB springs after 2001?

Also, there seems to be a fair amount of creep with the LEM trigger. Is this normal, due to the pre-loading of the hammer?

Thanks,

Kent

 

[JLStorm]

I think by keeping the TRS you get the V2 LEM vs the V1 LEM. The V2 is heavier, but I forget the break weight...it is around 7 or 8 pounds though I think. I would wait until someone else responds because I have HK do my LEM conversions, so I am not really qualified to answer.

By creep do you mean the travel before the trigger breaks and the hammer falls? Among other things this serves as a safety feature, otherwise you would basically have an SA trigger with no safety.

 

[Big Bore]

When keeping the standard TRS and FPB in an older USP/C pistol you should get a trigger pull of around 5 pounds.
It is in the P2000 and SK that you get the heavier pull if you leave in the factory TRS or FPB. In the P2K/SK V2 is normal FPB and TRS, V1 is both spring replaced (5 pounds), and V4 is only the FPB replaced (7 pounds).

If your pistol is AF or newer it will have a heavier TRS than mine did doing an AA pistol. In 2005 HK switched to a heavier TRS for all the USP/C and P2K/SK pistols. So if you have an AF or newer you will have about a 7 pound pull. I posted this info last week on the LEM trigger job post, second to last post on the last page at this time, and this is direct from HK-USA.

If you have an older pistol I must ask, did you rack the slide first and pre-load the hammer spring before measuring the trigger pull? If not then you have a 10-11 pound pull. The slide must be racked and the hammer spring pre-loaded before you get the light pull.
Also, did you keep the USPC hammer spring or use the one in the kit? The kit spring adds about a pound to the trigger pull.
And last of all, no two guns will be alike. I may get a 4.75 pound pull and you a 4 or a 5.5. There are a lot of things that come into play.

 

[Kent Frazier]

By creep do you mean the travel before the trigger breaks and the hammer falls? Among other things this serves as a safety feature, otherwise you would basically have an SA trigger with no safety.

Maybe creep wasn't the correct word. What I mean, there is travel before the trigger meets ANY resistance. This is only when the hammer spring has been pre-loaded (slide racked).

 

[JLStorm]

Maybe creep wasn't the correct word. What I mean, is there is travel before the trigger meets ANY resistance. This is only when the hammer spring has been pre-loaded (slide racked).

It is because the hammer is already pre-cocked, you will notice the hammer moves without resistance during this time. It is also a marketed as a safety feature, should someone be negligent enough to stick their finger in the trigger guard before they are ready to fire, or be ready to fire and have muscle contractions due to stress it may help avoid the trigger breaking like an SA trigger would without a safety. Basically if that travel didnt exist you would have a single action trigger with no safety, and that would not go over well with any departments or agencies...or most individuals for that matter.

 

[Kent Frazier]

When keeping the standard TRS and FPB in an older USP/C pistol you should get a trigger pull of around 5 pounds.

That is what I thought.

If your pistol is AF or newer it will have a heavier TRS than mine did doing an AA pistol. In 2005 HK switched to a heavier TRS for all the USP/C and P2K/SK pistols. So if you have an AF or newer you will have about a 7 pound pull. I posted this info last week on the LEM trigger job post, second to last post on the last page at this time, and this is direct from HK-USA.

Reiteration of part numbers from HK-USA:

To lighten the LEM pull on the USP/C pistol you will need part numbers
214192 Firing pin block spring USP/C if the gun was made before 2005
209296 firing pin block spring for guns made 2005 or later.
209266 Trigger return spring

OK, this is where I think I'm getting confused. Does the above part number refer to factory LEM USP/C's or all USP/C's? If the latter, it seems to contradict what I quoted at the beginning. My USP/C is AB.

If you have an older pistol I must ask, did you rack the slide first and pre-load the hammer spring before measuring the trigger pull? If not then you have a 10-11 pound pull. The slide must be racked and the hammer spring pre-loaded before you get the light pull.

Yes. To be honest, I can't feel much difference between pulling the trigger with the slide racked or not.

Also, did you keep the USPC hammer spring or use the one in the kit? The kit spring adds about a pound to the trigger pull.

I kept both the USPC hammer and TRS springs. I did NOT use the ones in the kit.

And last of all, no two guns will be alike. I may get a 4.75 pound pull and you a 4 or a 5.5. There are a lot of things that come into play.

I understand this. I'll take it to one to the local gun stores and see if they can check the trigger pull for me and post the results.

I hope you know that I and others really appreciate your time and patience.

 

[Kent Frazier]

Something is Seriously Wrong

I tested the trigger pull using one of my local gun stores trigger pull gauge (a Lyman digital like Big Bore's). The trigger pull with the hammer pre-loaded was 11 pounds 6.5 ounces!

 

[Big Bore]

Something is not right. That is the un-preloaded weight. If it is 11 pounds plus something is grossly wrong. It might be time for a smith or HK to take a look at it because that sounds like the first part of the hammer is not pre-loading the hammer spring and you are getting a standard DAO pull. Your kit that you put in did have a two-piece hammer with a spring on the side didn't it? If it has a once piece hammer and no spring someone sold you the standard DAO parts which would give you an 11 pound pull.

The part numbers I ordered when converting the P2K/SK to lighter LEM were: Firing pin block spring # 214192
Trigger return spring # 214164.

The part numbers HK-USA gave for lightening the LEM trigger pull are:214192 Firing pin block spring USP/C if the gun was made before 2005
209296 firing pin block spring for guns made 2005 or later.
209266 Trigger return spring

So the discrepancy is in the TRS (see HK-USA note below). The FPB is the same for guns older than 2005 and why the different part number for the TRS I do no not know. Someone a few months back said the TRS springs sent him by HK had a different angle on the legs than on the ones I used so HK may have changed that also. I do know if you order the parts I listed on the first page of the post you should end up in the ballpark with what I got. Even with the new pistols there should not be more than a pound difference.

For the difference you are getting I think something is wrong and the hammer is not pre-loading. Make sure the hammer parts are put together correctly and that the hammer spring (the one on the side of the hammer) legs are positioned correctly. If they are out of position I do not think the hammer will go into the pre-load condition.

Note***Here is a post from HK-USA in answer to your question over there:
The 209266 is a new spring it is what we are now using to convert to light LEM. If you are happy with the trigger pull on you LEM there is no need to change to the newer trigger return spring.

 

[Kent Frazier]

RESOLVED

...
For the difference you are getting I think something is wrong and the hammer is not pre-loading. Make sure the hammer parts are put together correctly and that the hammer spring (the one on the side of the hammer) legs are positioned correctly. If they are out of position I do not think the hammer will go into the pre-load condition...

Thank you again Big Bore!

I disassembled my gun, leaving the trigger intact, and reassembled. I'm not sure what I did the first time, or what I did differently but it is working now. I took it back to the gun store to check trigger pull. Results follow:

With Compact hammer spring; 4 pounds 11 ounces.
With LEM hammer spring; 5 pounds 6.5 ounces and 5 pounds 1 ounce (tested twice).

This is with the compact TRS.

I decided to use the LEM hammer spring and the slightly heavier pull.

Kent

 

[Big Bore]

EXCELLENT! I am so glad you are not getting the results you should. It makes a world of difference when it works correctly doesn't it!