[mneblett]

I have a USP Tactical date code AG that I did an LEM swap on years ago. Works great. I'm now doing an LEM swap on a USP 9 date code KD. The catch and control latch are a lot different on the 9 compared to the Tactical. Now that it is all assembled, the hammer does not pre-cock. It's essentially double action only. Did I do something wrong?

Is the old catch/latch assembly not compatable with the LEM trigger?

Bingo -- no. Same issue when converting my KI USPc to LEM.

Can I get a new catch and latch to replace the old style and make it work?

Yes. The new catch and the LEM hammer work together.

ETA: See TooSixy's LEM parts conversion lists in the Reference section.

 

[mneblett]

Start here: http://www.hkpro.com/forum/hk-reference-library/172503-individual-lem-part-numbers.html

If it turns out you have all the correct parts, we can start looking into whether there is an installation issue.

 

[mneblett]

I have assembled it and disassembled it several times. The seer keeps not catching the hammer. I can stick a punch between the magazine well and the seer and push the seer into position to lock the hammer in the precocked position when I pull the hammer back. The trigger then works great once but won't pre cock it again.

Are you *sure* the tiny spring on the hammer axle has its rear leg against the front of the hammer and its front leg on the *rear* of the sear?

Are you *sure* that the sear and the catch are on the correct sides of their respective legs of the sear spring?

Any chance the sear's spring leg is bent, such that it is not maintaining enough force to bias the sear into engagement?

 

[mneblett]

Well, at this point some pics would be helpful. Yes, the flat spring is the one to which I am referring. I would want to verify that the sear leg (the left-most leg) is firmly biasing the sear to the sear.

I found this old thread showing the old and new sears in post #2, but this thread indicates that the old and new should not make a difference.

One pic that would be very helpful would be one of the cocking piece (the part that is inserted into the bottom of the hammer and rides on the hammer axle with the hammer). Obviously, if this part is not positioned correctly in the hammer slot, you'd have a cocking issue.