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Discussion Starter · #1 ·
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? Can I get a new catch and latch to replace the old style and make it work?

Thanks for any and all help!
 

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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.
 

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Discussion Starter · #3 ·
I have a newer USP 9 so I took the catch and latch out of it and put it into the gun I'm trying to do the LEM conversion on. The hammer will still no pre-cock.

I could not TooSixy's list.
 

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Discussion Starter · #5 ·
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.
 

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Post a pic of the right side of the frame where the hammer axle is. Did you install the hammer axle correctly?

All pre-KF USP's will need some modifications to the frame for LEM conversion, among other things.
 

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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?
 

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Discussion Starter · #8 ·
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?
I am sure about the position of the legs of the spring against the hammer and the sear. It matches a working LEM trigger I have to look at.

If the sear spring is that flat spring that sits between the magazine well and the sear/catch, then I am fairly confident they are in their correct positions and pushing both components towards the hammer.

I have no clue if the sear's spring leg is bent. :)

I really appreciate the help and welcome it.
 

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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.
 

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Discussion Starter · #10 ·
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.
I will post pictures as soon as I figure out how. In the mean time... you are a very smart man because when bent the flat spring to add more pressure to the sear, the gun started to work flawlessly. When I would pull the trigger, the hammer would cycle. When I pulled the hammer back with my thumb, the sear would do its pre-cocking thing and the trigger pull was normal LEM. However.... then I put the slide on. When the slide cycles, the hammer won't pre-cock. It's a double action only gun. I can still pull the hammer back with my thumb and it pre-cocks it. But cycling the slide does not pre-cock it. Any thoughts on that sir?

Thank you soooooo mouth for the help thus far!
 

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Discussion Starter · #11 ·
What is happening is that the hammer will not pre-cock when the disconnector is depressed. When I thumb cock the hammer, the disconnect is not touched and the hammer pre-cocks just fine. When the slide cycles and cocks the hammer, the disconnect is depressed by the slide and the hammer will not pre-cock.

Any ideas of how I've messed this up? :)
 

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Did you or someone else modify the frame to allow the fitment of the LEM hammer axle? If no modification has been done to the frame, I'd really like to see a pic of the frame as stated in an earlier post.

Unless you're keeping the DA/SA safety/control lever.
 

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Discussion Starter · #13 ·
I do not see any way to post a picture on this forum. If I knew how, I would love to post a picture. Yes, the frame has been modified so the LEM hammer axle fits all the way in and is flush on both sides.
 

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Discussion Starter · #15 ·
Give me just a few minutes and I am going to post a video.
 

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Discussion Starter · #18 ·
I very well could be. What is the hammer strut? :)
 

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Discussion Starter · #19 ·
I just looked up the hammer strut. I'm using the hammer strut that came with the pistol that has a date code of KD. Is that is that what I should be using or do I need a newer or older strut? Thank you so much for helping me with this.
 

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You need the new hammer strut. If you're buying from HKParts, they have the wrong description on the old hammer strut. It is NOT the new-style strut.




ETA: Use the hammer strut that came with the other gun (USPt) and see if it solves your issue.
 
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